In better times, the United Auto Workers might have opposed the uprooting of 3,400 mostly elderly residents of a rundown section of the city called Poletown.

That would have been in keeping with the kind of social activism that distinquished the union from its many bread-and-butter-minded brethren in the labor movement.

But these are the worst of times for the UAW. Faced with a choice of supporting a new General Motors Corp. plant that is expected to provide 6,000 jobs, or backing Poletown residents who reluctantly are moving to make room for GM, the union is going with the plant.

"It is a matter of balancing the pain," said M. L. Douglas, vice president of UAW Local 22, which represents 9,000 Cadillac workers. "We have feelings about uprooting a lot of older people; but with the way things are going, we can't afford to lose those jobs."

It is the season of hard choices for the nation's premier industrial union -- "the most troubled time in our history," according to UAW President Douglas A. Fraser.

The reason is that the car the union drove to greatness over the last 46 years has skidded off prosperity road. Chrysler Corp., the nation's No. 3 automaker, has been riding perilously close to bankruptcy since 1979. Ford Motor Co., No. 2, has been trying to steer away from a sales decline that threatens to send it down the same road traveled by Chrysler. General Motors, No. 1, the first of The Big Three to be unionized by the UAW, sprang a $763 million leak last year -- the second time since its 1908 founding that the company lost money. In all, U.S. automakers dropped an estimated $4.2 billion in 1980, the largest loss in the history of the domestic auto industry.

Both labor and management have blamed each other for the present difficulties. Management has charged the union with "excessive" consumption of wages and benefits and has suggested that the UAW is the victim of its alleged greed. The union has accused management of, well, mismanagement.

But both groups came together to oppose a "common enemy" -- the foreign car, which they claim is aggravating this nation's financial and unemployment problems by gobbling up an undue share of the domestic market. This marked a right turn for the UAW, which in the past had championed the liberal "free trade" philosophy.

It wasn't the only compromise born of economic necessity.

Though highly regarded and greatly ridiculed for its success at the bargaining table, the UAW in the last 16 months has sacrificed a record $1.068 billion in negotiated wages and benefits in a desperate effort to save jobs and the life of Chrysler Corp. UAW president Fraser called the most recent giveback of $622 million "the worst economic settlement we ever made."

On that point, he has an amen corner. "You know," said Catherine Garrett, 39, a single mother and laid-off Chrysler assembly line worker who lives on the west side of this city, "I don't have any hangups about the union. It's doing its best. But the union's back is against the wall, and I don't think there's much it can do to help me or anybody else at this point."

Fraser and his lieutenants insist that, despite its problems now, the UAW remains "strong, resilient . . . a survivor." But the problems are many. Consider:

UAW membership dropped from a record high of 1.53 million in 1979 to 1.24 million last month, some 2,000 less than the union's recession-wracked rolls of 1958. Union officials agree with industry contentions that much of the latest loss is permanent.

Because of the membership decline, the union was losing up to $1 million a month in income last fall.

To cut costs, the UAW, headquartered here, eliminated 81 of its 850 international staff positions. At least 20 of the cuts affected union organizers -- key figures in any membership drive.

Local UAW units also are cutting staffs. Some, like the once famous Dodge Main Local 3 in Hamtramck near here, have died along with the plants that employed their members.

Fraser, one of the lowest-paid presidents of a major union, says he might have to take a cut in his own $62,000 annual salary "if things get worse."

The already bad conditions are testing the union's willingness and ability to live up to the ideals voiced by the late UAW president Walter P. Reuther. "The labor movement is about changing society," Reuther said in a book interview with authors Frank Cormier and William J. Eaton. "What good is a dollar an hour more in wages if your neighborhood is burning down? What good is another week's vacation if the lake you used to go to . . . is polluted and you can't swim in it and the kids can't play in it?"

In a way, Local 22 vice president Douglas faced those questions when a group representing Poletown residents asked him to speak against the GM plant, scheduled for completion in April 1983. The company says it needs the new $500 million structure to boost production of Cadillacs and of Fisher Body frames for other GM cars.

The GM plant will take 500 acres of land located here and in adjacent Hamtramck, and will be built partially on a site now occupied by Chrysler's defunct Dodge Main plant. Detroit, which will have most of the project, and Hamtramck are spending an estimated $199.7 million to get the new plant site ready.

"They asked me to come and speak and to try to get the local to do something to help them stay in their homes," Douglas said of the Poletown residents. "But I had to tell them that they were putting me in the middle on this thing. I can't, in good conscious, speak out against that plant when there are so many families around here out of work.

"This is a terrible situation, with the economy and everything. The union is not siding with the company on this. . . . It is a matter of balancing the pain," Douglas said, adding that the Detroit city government "will take care of the people who have to move."

No one in the UAW's hierarchy is visibly worried that the union will renege on the ideals that have brought it to international prominence since its birth in 1935, and no one is saying that the UAW might succumb to its present difficulties.

But most of the leaders agree that the union is on the defensive, and that the UAW must cope not only with the ravages of an errant economy, but also with charges -- from friend and foe alike -- that it has grown fat and happy and has become the victim of its own success.

For example, listen to a ranking Detroit city official and former UAW member who, for political reasons, requested anonymity.

"I worked in the auto plants and joined the union because the union was a way I could protect my rights," the city official said. "But a lot of us back then also felt that we had to do something to protect the union. Too many of these workers today don't seem to feel that way. They are coming in and taking benefits and not really working. . . . They're not committed to the work, to the union or to themselves, and they're screwing it up for everybody."

A similar, on-the-record comment came from Robert Leak, 40, a welder-repairman and UAW committeeman who represents 240 workers at the Ford Rouge Plant in nearby Dearborn.

Said Leak: "I don't buy that stuff that our pay is hurting the companies.

But I do think some rank-and-file attitudes will have to change if the union is going to survive. . . . We have too many people who skip work, get in trouble with the foreman, and then come running to the committeeman to take care of it for them."

Fraser gave some credence to the charges. "It all depends on where you look and who you talk to," he said. But he denied that the fat-and-happy behavior is characteristic of much of the union's membership or leadership, or is indicative of how the union wil face future challenges -- at and away from the bargaining table.

"Maybe I'm not objective. But I think I could make a case that we never relaxed in our mission," the UAW president said.

UAW members now earn an average hourly wage of $10.45 -- plus another $7.05 hourly in other benefits -- because they are employed in an industry "where the workers have been very, very productive" and where the companies "have been very, very profitable," Fraser said. He said the domestic auto industry's steep decline in profitability largely is the result of economic forces -- inflation, recession, foreign competition and alleged corporate mismanagement -- beyond the normal control of the UAW or any other union.

Whether or not he is right, Fraser's feeling that the union is threatened with loss of control over its product and destiny is shared by some rank-and-file elements who also say that, now, for the first time in their association with the UAW, they feel vulnerable to corporate/economic whims.

"The corporations are pushing the UAW back and back," said Joseph Allor, 33, a "15-year man" who works in the paint shop of a Dodge Truck plant here. "We're giving up things and losing ground. The leadership is doing its best to protect us and I think most of us back the union. But we're getting ripped right now."

To counter that sentiment, the UAW leadership is telling its Chrysler members that their concessions to the company were offset by gains such as membership on the board of directors, agreements to include workers in formerly exclusive management decisions such as plant closings, and profit sharing. Those are items that the union fought for in the past, but failed to get from a healthy auto industry.

To the members in non-Chrysler units, the leadership is saying that the UAW is prepared to seek the same counter-concessions from other companies -- Ford and General Motors are of primary concern -- that also might ask for reductions in negotiated wages and benefits.

"We're not disposed right now to open negotiations with Ford or GM before our contract expires in 1982," Fraser said. "But if they should ask for concessions, whether it be now or in '82, they'd better be ready to talk about a whole range of things. They won't be able to just come to us and say: 'Well, look here, we'd like you all to do for us what you did for Chrysler.'"

"It won't be that easy," Fraser continued. "They'd better be willing to talk about more representation on boards of directors, more worker input at the plant level -- not necessarily in that order -- but things like profit-sharing and financial disclosure, agreements to stop giving union work to outside contractors. . . . They'd better be willing to talk about a lot of things formerly considered the exclusive prerogatives of management."

But, Fraser conceded, the bargainin g table as a tool for progress necessarily will have limited use in the future because of basic, structural changes in the national economy. He said that means the UAW in particular, and the labor movement in general, will have to rely more upon the public to make and protect gains for organized workers.

"I would argue that the labor movement has to start moving more toward seeking solutions on the legislative front, and in the local, state and national communities, because we can't find all of the answers to workers' problems at the bargaining table," he said.

Such a strategy contains a quid pro quo that means, rather than abandoning broader social concerns in times of economic crisis, the UAW will have to do more to defend them, Fraser said.

"It's going to be a tough battle, but this isn't any organization whose history says that your only mission in life is to go out and to try to get more from the employers in terms of wages and benefits," he said. "We have in the past and will in the future continue to be an instrument for social change, regardless of our size."