DETROIT, SEPT. 21 -- United Auto Workers officials today turned their attention to General Motors Corp. in hopes of winning many of the same job-protection promises they got last week in a tentative agreement with Ford Motor Co.

Sources on both sides of the GM-UAW talks said that the negotiations will be difficult, and several expressed fear that the bargaining could end with a strike against the nation's biggest car maker.

But both sides also clung to hope that loopholes in the UAW-Ford pact could give GM the maneuvering room it needs to reach a similar agreement without a walkout.

"The Ford contract was deliberately designed to give GM a chance to accept it, or some version of it," one UAW source said. "There does not have to be a strike, even though a lot of things can happen to cause one," he said.

The linchpin of the Ford contract is the $500 million guaranteed employment numbers program, an anti-layoff provision designed to protect the jobs of that company's current 104,000 UAW-represented employes over the next three years.

The provision restricts Ford's ability to use overtime employment to extend layoffs. It reduces the number of jobs that can be lost through attrition -- resignation, retirement, death -- a process that normally reaches about 6 percent of Ford's U.S. production work force each year. It also limits Ford's ability to outsource -- to rely on non-UAW labor, foreign and domestic, for automotive components.

But the big loophole would allow Ford to lay off workers if sales of U.S.-made cars skid, provided that skid is not causes by competition from the company's own foreign-made imports.

UAW officials acknowledge that Ford is more efficient, has lower production costs and higher profits than GM and that Ford, as a result, is in a better position to offer strong job-security provisions.

"But we were realistic," one UAW source said today. "We know that they're going to have to be some differences at GM, and this contract provides that leeway," the source said.

The UAW probably will not try to get GM to rescind the 30,000 layoffs stemming from scheduled plant closings between now and 1989. And the union may have to swallow some additional layoffs because of market conditions -- as provided in the Ford contract, according to UAW sources.

But the UAW will fight any attempt to dismiss as many as 60,000 workers in GM's 120,000-worker components divisions. "We'll go to war over that," a union source said.

Alfred S. Warren, GM's vice president for labor relations, and other ranking GM officials repeatedly have said that they can offer the same kind of job security provided at Ford if GM could slice its component-manufacturing costs. Cost-cutting in that regard often is achieved by closing plants and shifting work to usually less-expensive, nonunion labor. Besides the 30,000 GM jobs that will be lost through plant closings, GM has identified 58,000 other positions that could be scrapped by outsourcing component work.

Both UAW and GM officials said today that they will take about another week to study the Ford proposal in bargaining subcommittees before revving up main-table negotiations, which were held in abeyance pending the Ford settlement.

Bargaining at both auto companies was meant to replace contracts originally scheduled to expire Sept. 14. The GM-UAW agreement has been extended indefinitely, and the current Ford agreement will continue until Sept. 30, when the union's rank-and-file members are expected to complete voting on the new contract.

A new strike deadline probably will be set for GM on or shortly after Sept. 30, bargaining sources said today. Maryann Keller, auto industry analyst with Furman Selz Mager Dietz & Birney in New York, agreed that the Ford contract contains significant loopholes that could make it acceptable to GM.

In addition to the right to lay off for economic reasons, the Ford agreement also encourages the reduction of job classifications on the plant floor, she said. "The contract seems to recognize the cyclicality," the frequent ups and downs of the auto industry, she said.

However, other analysts said that they are worried about another part of the Ford contract that requires any buyer of a Ford subsidiary to take the new UAW labor agreement along with the deal.

That carry-over provision could make it tough for GM to divest itself of an unprofitable division. And it would make it even more difficult to reduce its protection costs, which are an estimated 10 percent higher per car than Ford's, analysts said.