We had been in China for almost two weeks when I caught my first glimpse of what might have been a bulldozer. It was just a quick flash of a hazy silhouette on a distant hill, as our train rolled south from Wuhan to Changsha. But it ended a long quest.

It was back in Peking that I had remarked, "Gosh, what these people could do with a bulldozer." Wherever we looked, we saw a building or street under construction by straining men and women, with only wheelbarrows and shovels at their disposal.

"They've got them," said George Bush, the former chief of the U.S. Liaison Office in Peking and the head of our 13-member touring party. "I saw them when we were here two years ago."

And so began the search. In Peking, there were trucks and buses galore. There were even a dozen street-sweeping-and-washing machines out on Tien An Men Square to clean up after a giant reception for a visiting Cambodian leader. But not one bulldozer did we see.

As we traveled across the country, we continued to see impressive evidence of China's reconstruction. There were brigades of men and women, young and old, turning earth with shovels and hauling it this way and that, in carts of all sizes and descriptions. It was almost as if Chairman Mao had left an instruction in his will, "Let no pile of earth remain unmoved."

But never a bulldozer. From the windows of cars and trains, and every time we landed or took off in a plane, I scanned the landscape. For three misty days on a Yangtze River steamer, I went out on deck and stood at the cabin window, thinking surely one would appear in the fields.

But in more than 4,000 miles of travel through six provinces in 16 days, there was only that one glimpse of what might have been a bulldozer.

I dwell on that subject, because I came back from this first visit to China with the feeling that its future - and the future of its relations with the United States and the world - is directly tied to the transition from human labor to bulldozers, the reach for a modern industrial economy.

That is not to say that economics is more important than politics; only that it is more visible. As a novice, I could not judge what is happening politically in China a year after Mao's death.

Both Bush and James R. Lilley, a Chinese-speaking government official who served with him in Peking and accompanied him on this trip, said they found China "much more relaxed today" in its internal politics than when they left two years ago. Bush's judgment is that the collective leadership under Chairman Hua Kuo-feng has at least the appearance of stability.

While they speculated on political matters, the rest of us tried to make sense of what we saw taking place in China's economy.

J. Hugh Liedtke, chairman of the board of Pennzoil Inc. and a former business partner of Bush's had last seen China as an American aviator in World War II. "It's hard to recognize it as the same country," he said, even if much of the technology in the steel and machinery plants we visited was "25 years out of date."

The absence of beggars, cripples or ailing oldsters on the streets, the well-nourished and healthy young people in the cities, the growth of farm production even in backward Tibet, the reported success of family planning and social welfare efforts in most of the places we visited - these things were noted by others in the predominantly conservative group of travelers, including former Republican National Chairman Dean Burch, James E. Baker III, chairman of the 1976 President Ford campaign, broadcaster Lowell Thomas and Texas State Rep. Chase Untermeyer.

But if the progress was evident, so was the fact that it is being fueled, for now, largely by the energy of China's masses. The leap to an industrial society, let alone a post-industrial service-education-technology society like the United States, is still somewhere in China's future. China has the nuclear weapon, but every time we changed money, or paid a bill, the calculation was done with an abacus. As former Secretary of State William P. Rogers, also back for a visit, noted, the United States feeds itself - and helps feed the rest of the world - with 5 per cent of its population on farms. In China, 80 per cent of the people work on land to keep the nation from starving.

The difference that measures is incalculable - for the humans involved and for the society. It is the difference between a piece of modern farm machinery spreading fertilizer and women carryint buckets of nigh soil from the village to the fields, shifting the pole on which the two buckets are balanced from one shoulder to the other.

It is the difference between a tractor pulling a disk and harrow over a field in Iowa and lines of people, in the dusk outside Chungking, swatting at the ground with hoes. It is an old man struggling up a hill in Tibet, bent double by the load of barley on his back.

It means that when the pigs come to market in Kweilin, they ride not in a truck, but in a bamboo basket bouncing from a pole balanced on the shoulders of two men. And it means that when gravel is needed for a project in a Hopei commune, schoolchildren sit on the ground with hammers and break rocks into fragments.

"The Bushes and their friends," our official host, Hao Te-ching, president of the Chinese People's Institute of Foreign Affairs, told us at the welcoming banquet in Peking, "will observe the Chinese people are in high spirits and working hard to carry out Chairman Hua's strategy to make China a powerful and modern socialist country by the end of the century."

Working hard? Yes. In high spirits? Not visibly.The liberation of the spirit that depends on the lifting of the burden of hard, physical labor - of substituting bulldozers for human backs - is still somewhere in the future for China's people.

ALMOST EVERYWHERE we went, there was a standard explanation for the economic problems of the last two years: "The Gang of Four." The phrase, "Smash the Gang of Four," was so recurrent that Chase Untermeyer gave it an acronym: the SMOGOF speech.

We heard SMOGOF from commune and factory revolutionary committee chairmen, party secretaries and pretty student guides, from one end of the country to the other - always with persuasive local examples of how the Gang of Four had fouled up their particular operation.

Bush came away saying that one of the things he learned from the trip was that "this was much more than just a Peking power struggle. It permeated the country. It was much more widespread that I had believed."

The four - Chiang Ching (Mao's widow), Wang Hung-wen, Chang Chun-chiao and Yao Wen-yuan - occupied positions of great power before Hua turned against them and ousted them, a month after Mao's death. Whether they did all the nefarious things now being attributed to them is impossible for me to judge.

Here is the kind of thing we heard from the boss of the Chengtu Measuring Instruments and Cutting Tool plant, employing 4,800 people: "They did a lot of damage to this factory. They threw the people into confusion, and for a time production almost stopped.

"Many of the workers stopped working and engaged in debates." Those debates had been an accepted feature of Chinese life from the time of the Great Cultural Revolution in 1966. But now they are seen as economically costly.

Last year, he said, the plant reached only 60 per cent of its production goal in the state plan, but "this year production has doubled. We will reached our goal for the year tomorrow [Sept. 30], and the final quarter of the year will be in excess of our goal."

A few days later we heard a similar story at the Chungking Iron and Steel Corp., with 40,000 employees (a corporation, in Chinese terminology, refers to an economically integrated unit - in this case, spanning everything from coal mines to rolling mills):

"Great damage was done by the Gang of Four. They tried to undermine our leadership. We were all called capitalists. We could not work. We had no peace, no tranquility. We were pulled from one place on one day to another place another day. They raised unreasonable demands. They formed factions and wanted to carry out factional activities."

His voice was rising to an emotional pitch as he recalled those days, but then came the magic phrase, SMOGOF, and now, he said, the norms are being exceeded.

It really was hard to know what to make of these recitations. On the one hand, it was by no means clear that the "factional activities" have ended. Szechwan has the reputation of being a "troubled" province, closed for long periods to outsiders, and in both Chengtu and Chungking we saw small posters calling on the populace to "stamp out the diehard followers" of the discredited Gang of Four. Some of the local names, we noted, had been crossed out - not necessarily a healthy sign for them.

On the other hand, we all knew - and our official guides acknowledged - that had we made this trip a year earlier, we would have heard not one word spoken against the Gang of Four.

Lin Ching-yun, the ministry of foreign affairs information official who was in our party, assured me that "they were hated" by the people for a long time.

"Even when they were in power?"

"Yes," he said, "but we could speak of it only in the family, not in public. They were very clever. Whenever there was trouble, they blamed it on others. But the people knew who was really to blame."

A week or so later, when we were better acquainted with our Chinese escorts, I asked a more senior member of the group, Fan Kuo-hsiang, a diplomat with years of experience in Europe, if it were possible that such a nefarious group could again unsurp power.

"I don't know," he said, "I hope not. But it is impossible. I am prepared for it. We have had 11 factional struggles since the beginning of the Chinese Communist Party. We may have more."

Thinking about it, you had to hope the factories and farms really are exceeding their goals this year. If not, someone else will be the fall guy. The Chinese no longer execute the losers of their power struggles. They place them under house arrest and subject them to public ridicule. One of our travelers found, in a Kweilin store window, a set of gross, ugly clay figures, cruelly caricaturing the deformities of the Gang of Four. He brought them back to America as a vivid souvenir of the 11th - but probably not final - Chinese Communist factional war.

THERE ARE LOTS of Americans in China, trying to turn a buck or two by helping the Chinese break through into the industrial age. They are a curious, diverse crew - and, always, of course, they rush to greet any new visitors from home.

Sometimes that can have rather strange results. On the night we walked into the foreign guests' dining room in Wuhan, where we wound up our three-day trip down the Yangtze, we saw two other Americans seated at another table.

They must have been sympathizers. They had been here in 1972, and had been invited back, they said, so he, a chemist, could give some advice on a fertilizer plant. They had been in Wuhan for a couple weeks, but had been honored with an invitation to go to Peking for the National Day celebration.

She had had a little to drink. She complained that her husband's idea of visiting China was "just to go from one factory to another." But, she giggled, when they were in Peking, "I discovered the lovers' lane," just a couple blocks from Tien An Men Square. "They park their bicycles," she said, "and then it gets very quiet."

Bush asked her a question about where this was. She looked at him, as if for the first time, her eyes squinting to focus. "I'm not going to tell you anything." she said. "You were with the CIA."

NOT ALL the visiting Americans were that amusing, but their number and diversity said something about the increasing ties between the two countries. There was the Washington developer, in for the third time in five years to buy antique furniture. There was the American Telephone and Telegraph executive, invited to lecture on telecommunications and, incidentally, to look over the Chinese long-line switching equipment. There were the off-shore oil men, hoping to sell something called a jack-up rig. There were publishers, hoping to persuade the Chinese to allow them to open Peking bureaus.

In the last case, and often in others, the answer was "no." China isn't doing that much business with the United States. In 1973-1974, thanks to large-scale wheat purchases and some big "turnkey" industrial deals (in which whole plants were built and equipped by Americans and turned over to the Chinese to operate), China's trade with the United States brushed close to the billion-dollar mark. Last year, the figure was only one-third as much, and in the first six months of 1977, it dropped below the level of the same period in 1976.

Some attribute the downturn to balance-of-payments problems; others say China is favoring Western countries which have granted it diplomatic recognition. Hugh Liedtke, who is convinced that rapid development of China's major oil and gas resources is in the strategic interest of both the United States and China, talked to Foreign Trade Minister Li Chiang about an ambitious concept that goes well beyond the "turnkey" development. He wanted to sell the Chinese on a "total package" of equipment, management and technical advice, integrating the whole process from initial exploration to final distribution and marketing.

Bush, who accompanied him to the meeting, said the Chinese attitude was one of the "polite listening, no different than it was two years go." Liedtke said, "I just don't think we were on the same wavelength."

Even when they get a foot in the door, the American businessmen and technicians can have a frustrating time of it. We ran into four oil-field specialists from Texas and Louisiana at the hotel in Chungking, and heard an earful.

First of all, they were stir-crazy. Every time they went out the front gate on foot, they were surrounded by gawking mobs. On a visit to the zoo, one said, he noticed a big crowd gathering across from him, and thought, "Boy, that panda is really popular." "Then," he said. "I realized they were all looking at me."

The oil men had seen the Chungking acrobatic troupe six times, and by the time we got there, were reduced to card-playing and morbid speculations about a corpse that had been left lying on the street for three days before it was picked up.

Their professional dealings with the Chinese were equally puzzling and frustrating. They had been sent out by their companies to test and demonstrate sophisticated oilfield equipment the Chinese had bought as part of their continuing effort to examine the most advanced U.S. technology. They wanted to let them get anywhere near the wells.

"I asked one guy what was the depth of the wells," one said, "and he told me, 'Between 2,000 and 12,000 feet.' So I said, 'Well, we just better put in some slack.'"

Another said: "They'll send in a team of eight engineers, each a specialist in a different phase of the business, and they'll read all the specifications on every component part in the machinery. Then they want you to prove it can meet all the specs. It's no piece of cake. They're tough. But they'll never discuss the practical question of how it is best used."

"What they really want," said the third, "is the technology. That's why they buy the equipment. They ask you, 'How do you make this? How do you make that?' I say, 'How the hell do I know? My job is to operate it, not to design it.'"

"The price they pay," said the fourth man, in a rich Cajun accent, "I don't blame them. We really stick it to them. But it don't worry me. I got my ticket to Peking," he said, patting his pocket, "and home."

IT MUST OCCUR to every foreign visitor, some time on his first trip to China, what a remarkable thing it is that a society as populous as this can be organized so that it functions at all. Somewhere between 800 million and a billion people - one-fifth of the entire population of the globe - the mind boggles. Before I left, I was dreaming about endless waves of Chinese, all riding their bikes straight at me, passing forever over the bed where I lay.

The wonderment first struck me in Chengtu. We had been to Tibet and back, and on this evening, after dinner, we were on our way to the station to catch a train to Chungking.

It was two days after the National Day celebration. The buildings and parks were still decorated, and the streets were filled with people walking and biking almost aimlessly, in a holiday mood. Suddenly, I thought, "What would you do if somebody told you, 'See that these people are fed and housed and have something to do tomorrow.' What in the world would you do?"

You would either tell them to cope for themselves, knowing that some would do very well and others would not make it, or you would organize a massive bureaucracy to run things, and invent an ideology big enough to justify that system of planning and control.

The Chinese have done the latter, and we saw that system of ideological-bureaucratic control at work ever day of our visit.

At the most basic level, that of physical intimidation, it works like this: Three nights before National Day, we came back to the Peking Hotel from dinner, and found the street thronged with marchers, all headed for Tien An Men Square and a rehearsal of the big celebration. School brigades, work brigades, minority nationalities with the girls' cheeks elaborately rouged, ribbons on their braids and colorful embroidered caps - all were moving toward the square, urged on by a cruising sound truck, with a shrill, female voice crying, "Move faster. Close in now. Pay attention. Pay attention."

We were drawn irresistibly in their wake, and moved down the sidewalk to within a block of the square, where giant searchlights swept the sky in rhythmic arcs. We had observed nothing more hostile than some curious looks, but, as if an unseen signal had been given, we suddenly found ourselves confronting a line of youths - badges on their shirts - spread across the width of the broad sidewalk and advancing toward us with their right hands raised in the universal signal to halt. A line of green-uniformed People's Liberation Army soldiers, similarly spaced, were two paces behind them.

Little was said, but inexorably they moved forward, sweeping us and the other gawkers, block by block, away from the square and all the way back to the driveway of the Peking Hotel. Jim Baker, who knows something about the mobilization and movement of campaign crowds, said, "That's pretty efficient."

It was indeed. Not aggressive. Not pushing. But inexorable. We had no choice but to conform. Later, as we stood on the roof of the hotel, looking down toward the square, I thought of a story the Bushes had told us.

There was a particular Chinese official who hung around the Peking International Club, engaging in casual conversations with foreign diplomats and, they presumed, reporting his gleanings to higher authorities. He was a charming, cultivated man, and the Bushes liked him - knowing all the while what he was up to.

And then they learned that some years earlier, when Reuter correspondent Anthony Gray had been under house arrest in Peking for two years for some alleged security breach, that same charming gentleman had gone by Gray's house, picked up his pet cat, slipped a leash around its neck and hung it before the correspondent's eyes.

THE FOREIGNER traveling in China is pampered, protected and restrained beyond anything he desires. It colors his view of the country. As the Belgian historian Simon Leys warns in his newly translated book, the China the visitor sees is less the China of reality than a "shadow play" produced for him by the Maoist authorities.

A program of visits is organized and skillfully executed by the hosts assigned to your party. Banquets and toasts are exchanged, the requisite lectures on Taiwan, the Soviet Union and SMOGOF delivered.

The only Chinese one gets to know well are the people accompanying your party. In that respect, we were very fortunate. The Bushes' charm and Lilley's language skills overcame much of the natural reserve of the five men and two women who traveled with us, and, in some cases, led to a great feeling of rapport. As the discipline of the group loosened just a bit in the intimacy of travel, it was fascinating to watch the contrast in individual reactions.

Mr. Lin, the foreign ministry press man, played it strictly by the book, from beginning to end. On the second day in peking, we drove past the building of the People's Daily. On an impulse, I said I would love to stick my head inside, and bring "fraternal greetings" from the morning newspaper in our capital.

He looked at me as if I were insane, studied his schedule, and said, "No such visit has been requested. I will have to see if it can be arranged." It couldn't.

Neither could a friendly ping-pong game, designed to test his claims of prowess. Nor could anything else that had not been scheduled in advance. As his literal-mindedness became known to our whole group, we vied in ways of testing it.

Outside Kweilin, for example, our motorcade stopped to look at a 1,300-year-old banyan tree. "How do you know it's 1,300 years old?" asked one skeptic. "It doesn't look much over 1,000 years old to me." Lin said, deadpan, "They keep very good records in this province."

One day in Chengtu when he and I had lagged behind the rest of the group to stop by the local telegraph office, an incident arose that I thought would shake that icy discipline.

We turned down a country road, headed for the park built as a memorial to the 8th Century poet, Tu Fu, and a youth of 10 or 11, standing by the edge of the road, very deliberately reached down, picked up a clod of dirt and tossed it, hard and accurately, against the side of our car.

Lin and the driver exchanged glances, but the car did not slow for more than a second. "What was that about?" I asked.

"You saw something just now?" Lin said, with surprise. "I missed it."

AT THE OTHER END of the scale in spontaneity was Yang Chieh-chih, a Shanghai-born translator who had studied in England and visited Canada and the United States. A member of the Communist Party "but not a leader," he said, he blended his ideology easily with a delightful sense of humor and a flair for the vernacular. Once, in Tibet, when Bush was hesitating over a purchaser, Yang said to him, in a voice loud enough to be heard and enjoyed by everyone, "C'mon, I hear you're loaded. That's a drop in the bucket to you."

One day, I asked this young man - born in the year in which the Communists finally won China - what he thought the next 28 years of his life might bring. He answered, with great seriousness:

"We have made great progress, but we are still very backward in some respects. We do not have enough colleges and universities for the people who want to go and ought to go. We do not have good enough elementary and middle schools. We lost so much through the Gang of Four, and now it takes time to recover."

I asked Yang what the boys and girls he had grown up with it Shanghai were doing now. "Some are inf actories and on farms. Some in cadres, some in the PLA, some in the foreign ministry," he said. "I was very fortunate. When I was in England, my English friends used to say, 'Come, have a good time with us.' But I knew how hard people had worked in China to create for me to study abroad.

"So when school holidays would come, my Chinese friends and I would approach a teacher and say, 'Please, could you give us special instruction in this or that subject?' We felt that obligation."

Yang was special; he would have been in any country. You longed to meet others his age - the same age Mao and Chou En-lai were in the mid-1920s, when they trained their first cadres for the revolution that would win China more than 20 years later. For the future of China now rests in the hands of Yang and his generation more than it does with the aging and aged men of the Cultural Committee.

MAO IS NOW enshrined in a mausoleum in the center of Tien An Men Square - destroying its symmetry, some say. It opened on Sept. 9, and we were among the first Americans permitted to visit.

The tomb is about the size of the Lincoln Memorial, and not dissimilar in structure: a marble quadrangle, lined with columns and surrounded by beds of chrysanthemums.

You go up the stairs on the portico and enter the first chamber, dominated by a twice-lifesize statue of Mao seated in a chair and looking benign. Behind him is a huge, idealized Chinese landscape done, with incredible patience, in needlepoint.

You pass in front of the statue, turn right and go down a short corridor to the middle chamber, air-cooled, where Mao's catafalque lies in a bed of lilies.

Four PLA soldiers stand as an honor guard at its head. Under the glass cover, Mao is dressed in his gray uniform. His mummified remains look old and leathery. There has been no effort to romanticize his appearance.

MANY KNOWLEDGEABLE China-watchers have written that the current government, having given Mao a fitting burial-place, is now busy discarding his policies, one by one. But a reception in the U.S. Liaison Office, an East European ambassador known for his shrewdness, whispers urgently that it is unwise for a Western correspondent to write of the "de-Maoization" of China.

"They are not ideologically impure," he says of Vice President Teng Hsiao-ping and his colleagues. "They are just realistic and flexible, as they have shown in many ways. Please don't make trouble for them by propagandizing that they are 'de-Maoizing China.'"

After our visit to the mausoleum, I met with a veteran Peking correspondent from the same East European country.

I told him about the ambassador's plea, and he said, "Ah, yes. That is his theme. I don't write about 'de-Maoization,' " he said. "I write about 'de-dogmatization.' At this point, Hua and Teng and their friends can't get by without Mao. He is the branch on which they stand; cut him off and they fall. But the fact is that Mao's monument has grown smaller, just by standing still."

With that in mind, we watched the banners and posters on our journey for any clue to Mao's size. There were many places where his face stood alone, or in company with the pantheon of foreign heroes - Lenin, Stalin, Marx and Engels.

In more places, portraits of both Mao and Hua were seen, either in formal pairings or in a popular poster showing Mao Putting a fatherly hand on Hua's hand and saying, "With you in charge, I can rest easy."

But on our last day in China - in fact, en route to the Canton station to catch the train to the border - we saw a startling billboard. It was huge, probably 30 feet high, and it showed a giant likeness of Hua reading a volume of Mao's speeches. The picture of Mao on the cover of the book was one-sixth the size of Hua's face looming above it. And right next to the book, in Hua's other hand, was a red pencil!