Much of the history of the domestic auto industry has been shaped by union struggles against production speed-ups and mandatory overtime that, as a United Auto Workers journal put it, "made young men grow old."

Accordingly, most UAW members were elated in 1973 when their union negotiated tough restrictions on the number of hours and weekends its members could be forced to work overtime.

But today in Saginaw, Mich., where many UAW members regularly are working voluntary overtime while thousands of their union brothers and sisters are standing in the unemployment lines, that elation has turned to grumbling.

"It's creating a split" in the ranks, said Tom Wilson, bargaining council chairman for UAW Local 699 in Saginaw. "We fought hard to get voluntary overtime, but we don't like to see it used this way." The practice, he said, is keeping the unemployed unemployed longer.

About 2,051 of Wilson's 10,200 members are out of work at the Saginaw Steering Gear Division of the General Motors Co. About 8,000 Local 699 members are working in the plant, and an estimated 1,300 of the union members do voluntary overtime work on weekends.

The phenomenon is another of those peculiar, painful side-effects of an industry trying to struggle out of the grip of its own depression.

"We're having to make a lot of difficult decisions," said John Mueller, spokesman for GM's Saginaw steering gear unit. "We're aware of the people who are out of work, but we have a wildly fluctuating production schedule and overtime work in some areas is the most efficient way, sometimes the only way, to get our products out," he said.

Mueller said his plant is "undergoing tremendous changes" caused by GM's movement from production of rear-wheel-drive cars to the hotly demanded, more fuel-efficient, front-wheel-drive models. Some plant capacity is unusable in the changeover, which means a loss of jobs, Mueller said. Other production areas are booming, but given the current state of the national economy no one knows for how long, he said.

"We're faced with the tough choice of bringing more people on when the production schedule is up or going with who we have," Mueller said. "The problem is that the schedule can drop down again very quickly, and here you've gone out and brought back all of these people with no production to support them," he said.

Local 699's Wilson doesn't see it that way, however.

But the local union leader concedes that he's caught in a dilemma.