General Motors Corp. said yesterday that it is extending van production at its Baltimore plant until at least the summer of 2005, giving new life to an aged factory that many of its 1,600 workers feared would close next year.

The Chevrolet Astro and GMC Safari van assembly line came to a halt at 8:20 a.m. yesterday as workers anxiously awaited word on what they were told would be an important announcement.

There were cheers, clapping and shouts of "yes, yes, yes," when plant manager Tim E. Stansbury told workers of the extension via closed circuit televisions scattered throughout the sprawling factory.

Some workers thrust fists toward the ceiling. Others hugged their colleagues on the line or patted them on the back.

"It was a very happy day, it was overwhelming," said Walter "Bud" Plummer, who took over this week as president of United Auto Workers Local 239, which represents the plant's hourly workers.

"We now know that we are going to get a paycheck for at least a couple more years," Plummer said.

The celebrating was probably not limited to the GM workers.

"This is a wonderful victory for Broening Highway workers and another 1,600 people in the Baltimore area that work for about 15 companies supplying parts to the van plant," said David S. Iannucci, secretary of the state Department of Business and Economic Development.

Autoworkers have grown increasingly concerned about the future of the 67-year-old plant in recent years.

GM has been saying for a couple of years that the plant would remain open at least until the third quarter of next year. After that, the company said, the market for the vans would determine the plant's future.

With Astro and Safari sales off a combined 51 percent over the past three years, many workers feared that the market would not justify continued production after the third quarter of next year.

But a new GM market survey concluded differently. It said there would likely be a profitable niche for the vans in coming years, due in part to reports that DaimlerChrysler is considering halting production of a full-size commercial van.

As they left the plant yesterday, workers expressed relief with the announcement.

"A lot of my anxiety about the future of this plant disappeared this morning," said Patrick Burke, 36, an assembly line worker who lives in Glen Burnie. "I've been thinking about moving into another house. This frees me up to make that move."

Said Victor Harper, 38, a body shop worker who has been with the plant three years: "I was happy when I heard the news. I was thrilled. I couldn't believe it would be such great news."

Sen. Barbara A. Mikulski greeted workers as they left the plant. The Maryland Democrat told Harper that while no guarantees exist, the extension could lead to a bigger announcement in the future.

"As long as the plant remains open, there is a chance of us winning a new vehicle to be made here," she said.

GM spokesman Dan Flores said that a company market survey showed continued demand for the commercial versions of the Astro and Safari vans.

"It's a dynamic market," Flores said of truck sales. "Trucks now account for nearly 60 percent of our production. Who would have believed that five years ago?

"This market changes month to month. Who knows what is going to happen between now and the summer of 2005? There could be a market for a new vehicle, and this extension only helps Baltimore's chances. It can't hurt."

Stansbury told workers that they played a role in the company's decision.

He was referring to two recent industry surveys by independent sources crediting the Broening Highway facility with quality and productivity improvements.

Last month, a study by J.D. Power & Associates noted that the plant posted a 16 percent gain in quality last year, compared with an 11 percent gain in quality of all GM vehicles.

And on Thursday, the Harbour Report credited workers with a 0.6 percent improvement in productivity, something the report said was remarkable considering the age of the vans produced at the plant.

The Astro and Safari have not been redesigned since their introduction in 1984. Such redesigns usually make vehicles easier to assemble and improve quality.