NORTH TARRYTOWN, N.Y. (AP) _ With a recent make-over and a popular product, the General Motors plant in this village of 8,000 seemed secure.

But on Monday, the North Tarrytown plant employing 3,456 workers making minivans was marked for closing in three years as part of the automaker's big restructuring.

''We thought we had a good plant and were doing a good job,'' said Richard Cariello, just hours after General Motors Corp. announced the shutdown of its assembly plant 30 miles north of New York.

The closing of the plant built in 1900 to produce Walker Steamer automobiles will coincide with the retirement of the current generation of GM minivans.

The plant was only recently retooled to produce the sleek Chevrolet Lumina APV, the Oldsmobile Silhouette and the Pontiac Trans Sport.

The closing is part of a plan aimed at reversing a financial tailspin at GM, which also reported record 1991 losses on Monday of $4.5 billion, the largest annual deficit in U.S. corporate history.

In addition to North Tarrytown, the company said it would close a Michigan assembly plant and shut down operations at 10 other factories.

Management at the New York plant learned the bad news at 10 a.m. Fifteen minutes later, the assembly line was shut down and the workers were told, said Darwin Allen, director of media relations for the Chevrolet-Pontiac-Canada Group.

As the workers, most of them driving American-made cars, streamed out of the plant at the end of the first shift, most expressed shock at the news.

The plant once boasted a work force of more than 5,000, and government officials have battled for years to preserve the plant on the banks of the Hudson River.

In the early 1980s, GM threatened to close the plant, citing high utility costs and high taxes. But it stayed after the local government lowered the property taxes, funded training programs, got the plant a reduced electricity rate and persuaded Metro North to raise rail bridges so cars could be shipped by rail.

In return, GM built a $170 million paint shop, part of a $250 million investment to upgrade the plant and the centerpiece of a 10-year agreement state and local officials thought would keep the plant running at least through 1995, if not longer.

''North Tarrytown is not unique in having had the huge investment,'' said Allen. ''It's not a matter of good plant versus bad plant.''

GM was committed to trying to find jobs for its workers elsewhere or offering job training, he said.

Denise Dawson, a GM worker for 11 years, has seen two other GM plants where she worked shut down in that time - one in Freemont, Calif., the other in Kansas City. North Tarrytown would be the third.

''I'm a pioneer for General Motors,'' she laughed. ''I think they just want to make cheaper cars and they can do that elsewhere.''

It was the last bastion of blue-collar work in Westchester, a county known for several big-name corporate headquarters, including International Business Machines Corp.

North Tarrytown Village Administrator William Regan said the GM plant paid $1.1 million in village property taxes this year, or about 20 percent of its total.

''If it shuts down and nothing replaces it, there will be a serious effect on the area,'' he said.

United Auto Workers Local 664 President Donald Martino told reporters outside the North Tarrytown plant, ''I'm devastated. I can't believe it.''

''I live here in Tarrytown. Once they close here, this town will become a ghost town.''