FLINT, Mich. (AP) _ Workers at a General Motors Corp. plant that supplies important parts were preparing to strike Tuesday morning if a contract spelling out local workplace conditions remains unsettled.

A strike by the 6,800 workers could hurt GM's production system because the AC Rochester East complex is the sole source of parts like fuel pumps and spark plugs.

However, GM wouldn't characterize the the extent of the impact Monday.

''I can't speculate on that,'' said AC Rochester spokesman Dan Dolan. ''I won't tell you what's going to get hurt and when it's going to get hurt because that would be providing information to our competitors about our supplies,'' he said.

He also said he didn't know whether the United Auto Workers union would allow members at other GM planst to work with non-GM products, as it has at times in the past, because competition is so fierce.

The strike deadline is 10 a.m. Tuesday.

''They're still talking. I guess you have to construe that as progress,'' Dolan said late Monday afternoon. ''It's just a waiting game.''

Negotiators from GM and the UAW met over the weekend and again Monday. Officials would not discuss the specific issues involved, but said they were related to job conditions at the complex.

Wages and benefits aren't at issue because those topics have already been ratified by the UAW as part of a national labor contract approved last fall.

''There is a national contract in place, but every local union has local contracts with the plants where they work,'' Dolan said.

The strike threat is the second this year over local issues at a GM plant. The UAW struck for four days in January at a Shreveport, La., plant where compact pickup trucks are assembled. A tentative agreement was reached that included hiring about 100 new workers.

The AC East operation includes about 4,900 AC Rochester workers and 1,900 Delco Electronics workers. Both operations are covered under the same local agreement. The plant also make cruise control mechanisms and air, oil and fuel filters.