"In a real dark night of the soul, it is always three o'clock in the morning." --F. Scott Fitzgerald, The Crack-Up.

It is 3 a.m. all right, and the Iowa countryside outside his tourbus window is socked in a frozen and oceanic darkness.

But so far as anyone in nearby seats can tell, the soul of John Bowden Connally is on excellent terms with itself. If this state's Republican voters would heed the message he's brought to them through the day and night, Connally would likely tell you, much the same could be said of them in time.

Just ask him.

Connally, on a 40-hour, nonstop vote-gathering marathon in this state preparatory to Monday night's presidential caucuses, has been the bearer of glum tidings -- and promissory notes of hope. To Iowans in county courthouses, motel banquet rooms, roadhouses, college fraternities and tractor showrooms, the former Texas governor and Nixon administration Cabinet officer has painted an alarming tour d'horizon for the nation in the 1980s -- a decade, he tells them, of "danger, decision and dedication" for America.

At each stop, he has told crowds of the committed, the interested or the merely unoccupied -- most of them farming folk -- that they were the "best people God ever let live on this earth," but because their leaders were in "the throes of indecision" on every significant matter of domestic and foreign policy, they had nothing to look forward to but a serious and perhaps irreversible decline in the national fortune.

"It isn't enough to eat the fruit of the tree of freedom. We must plant new trees in the orchard of freedom," the fist-shaking Connally told an approving crowd of some 1,200 people in Waterloo Friday night.

He seemed ready to begin the plantinghimself in Iowa, and he more or less offered himself as the nation's head nurseryman for the coming decade.

The 62-year-old rancher-lawyer, long the smooth forward nub of Houston's oil and banking establishment, unpacked "a load of troubles" at the outset of each of his 19 arrangements up, down and across this state that has been heavily courted by presidential aspirants this month: The Russians and their Cuban retainers were getting their way in hot and cold contests aroung the world (Y'all check your maps when you get home and see for yourselves."), he told his audiences.

The dollar was becoming a monetary laughing stock. The future of Iowa farming and American enterprise in general was a hapless hostage of the oil cartel. The federal budget was in the hands of spendthrifts and incompetents at both ends of Pennsylvania Avenue, he warned.

U.S. trade accounts, the litany continued, were in calamitous repair, thanks especially to the wily and selfish Japanese. Cutbacks in military spending, carried on much longer, would render the Pentagon helpless in the face of the Soviet juggernaut on land and sea. The "global aspirations" of the American people, absent an early return of "strong leadership" to the White House, would be disappointed, perhaps terminally.

This Connally recitation, laid out in a Red Oak armory, at an american Legion wild game breakfast in Keystone, at a Waverly cattle auction and before downtown types in Des Moines, is followed by a prescription for hope and national redemption: the prospect of a Connally presidency.

Inflation poses no mystery, no mystery at all as to its cure. not for this Dorian Gray of a candidate, re-suited and freshly shaved for a 4 a.m. reception at George Henning's farmhouse in elberon.

The prescription:

Cut federal spending. Do away with deficits by using vetoes. Encourage saving and investment, with tax breaks for the middle class and a new depreciation schedule for large and small businesses. Free farmers and businessmen of 90 percent of the regulations imposed on them now. Get hold of the bureaucracy by reminding Congress that it can control what it creates.

Energy? Connally urged Iowans to "face up to the facts of life."

"A time of dangerous scarcity is upon us," he said. He told a crowd of 150 courthouse workers in Marshall town that the United States was already in an "extended war of resources" with the rest of the world over energy, and urged mining and burning of more coal, as well as expeditious licensing and construction of nuclear power plants.

Connally's pinstriped entourage and the sartorially unambitious band of journalists chronicling the candidate's progress across 854 miles of back roads through this farming state hit Bill Deal's livestock auction ring in Waverly Friday like nothing else in "at least 99 years," said one cattle trader on the scene.

And by any fair estimation, Connally's performance in Deal's sales ring -- his advance men fitted in an appearance between biddings on two holsteins -- was a theatrical and political tour de force. In cowboy boots and a perfectly tailored three-piece business suit, Connally told of a rural upbringing in Wilson County, Texas, a miserable blotch of land cursed with "the sorriest soil you fellas ever saw. Nothing like the land you work here." He talked of his boyhood adventures as a deliverman's helper on a San Antonio dairy truck.

Then he brought his campaign to something of a milestone. Asked by one green-capped dairyman in the amphitheater about the American dairyman's future, he told his questioner that, yessir, dairymen worked hard, but in hard times for farmers they would always have to make sacrifices to survive, even "if the government got off your backs."

"Let me tell y'all something. None of you have made the sacrifices for the dairy industry that I have. I got indicted because of it, if you want to know something. You think I don't know about milk producers and milk prices, you're crazy. Because I was trying to help you. And I was trying to tell the secretary of agriculture and the president of the United States they were wrong to set parity below what you needed."

No Connally aide could remember their man ever voluntarily bringing up in public his indictment and acquittal in 1974 on charges of accepting a bribe from the dairy industry for helping advance their interests in the Nixon administration.

The Soviets ranked first on connally's list around the clock. He said that they cast a pall over everything the United States stood for a world affairs and that "strength is the only thing they understand." What to do? Anticipate. Build up conventional forces. Arm Pakistan now.

Connally's explanation of America's trade imbalance dwelt on the Japanese.

They must be made to see, Conally said, that while the American people were basically free traders, they were fair traders first. If the Japanese weren't prepared to import more Iowa beef, for one thing, then they might be stuck with their Toyotas an TVs.

In a Connaly millenium, energy and inflation woes would be solved and the dollar restored to its rightful place in the hearts and minds of the world's central bankers.

While openly conceding the Monday caucuses to Ronald Reagan and George Bush, Connally stressed to Iowa Republicans his electability in the fall and effectiveness in the Oval Office once elected. He chided Reagon's "disciples" here for supporting the Californian simply out of a sense of loyalty for Reagon's past services to the party. Through inference Bush was dismissed as a "nice fella," more or less ineffectual.

How did the tall Texan play in rural, corn-fed Iowa? The farmers and small businessmen who turned out to see him were enthusiastic and admiring, but to many his image seemed too racy by half, too exotic and volatile.

Connally backers here like to think, however, that there are thousands of Republican votes ready to come their way Monday night, votes like the one belonging to Tom Murphy of Red Oak, a retired trucker. Murply came to the National Guard Armory Saturday afternoon to see what John Connally was all about. Murphy said he had been torn between Bob Dole and Reagan and had made a small contribution to Dole's state campaign.

After hearing Connally, however, Murphy said: "That guy makes me wonder. I'll tell you, he's got it on the ball a little better than the others. He's sort of a good combination of Harry Truman and Barry Goldwater. Those two wrapped up in one. I'll have to do some more thinking before Monday night."

They serve, too, who stare through frosted bus windows more than 40 hours without benefit of showers, toothbrushings or anything like real sleep. Consider the press corps or that small portion assigned by faraway editors to cover Connally's eve-of-the-caucuses marathon.

Connally's stamina, good cheer and extry-human equability were impressive. He proved an accomplished catnapper and a man with no brief against bus travel (he is on Greyhound's board of directors). It took little to gin him up for the next appearance down the road besides a Butternut candy bar, a Dr. Pepper (he's on the soft drink company's board, too) and a fresh suit.

The journalists, by contrast, took a terrible beating.

Somewhere before Elberon early Saturday morning -- though it could well have been in Iowa City late Saturday evening -- one member of the Connaly press contingent said of his predicament: "The Iowa Crisis. The 30th Hour. Journalist Held Captive." He demanded to see the Rev. William Sloane Coffin at once. And late in the night, not so much out of Fitzgerald soul darkness as dizzy antics, a television reporter demanded to know of a Connally press aide if "the governor believed in the forced busing of journalists to achieve election."