The tentative contract between General Motors Corp. (GM) and the United Auto Workers would allow GM to close a plant each in Michigan and Indiana and possibly shut down several other facilities, according to a detailed copy of the agreement.

The moves are the downside of job security pledges that the UAW won in the negotiations, including commitments for new products at 16 plants. About 74,000 hourly GM workers will vote on the pact starting this week, with a final tally to be done by Oct. 10.

Gregg Shotwell, a GM worker and frequent critic of the UAW, posted most of the contract details on the Internet. He said he received the agreement from a local union official who attended a Friday meeting in Detroit. He would not identify the official, but the accuracy of its contents was confirmed for The Associated Press by a union leader who requested anonymity because members have not yet voted on the pact.

The agreement would let GM sell or close a stamping plant in Indianapolis and close an engine plant in Livonia, in suburban Detroit. According to the detailed document, called the "white book," work at the Indianapolis stamping operation will continue or be reallocated to another GM plant "until such time as the plant can be sold to an outside buyer."

GM will study keeping the plant, but if it is not sold or kept, it will be closed "no sooner than December 2011," the document said. It employs about 850 workers, according to a GM Web site.

The Livonia plant, which now employs about 300, would remain open through its current product life cycle, which ends in 2010.

"The national parties will jointly explore opportunities for current Livonia seniority employees," the document said.

A stamping plant in Flint and a small powertrain operation in Parma, Ohio, near Cleveland, also may be in jeopardy, according to the document. For the Flint plant, under the heading "Product Opportunities," the document says only that the UAW and GM will explore opportunities for current Flint employees.

The document says no future powertrain products will be allocated to Parma, which also has a stamping operation that will continue with new generation products.

The document identifies as closing several smaller sites or factories that GM had previously said were going to be idled.

The Flint North engine plant will gain a new facility under the agreement. The document says GM will build three "lean, agile flex engine modules" at a new site near the plant. The new plant could build as many as 1,200 four- and six-cylinder engines per day.

Under the agreement, GM at present has no future product for the Orion Township assembly plant, which now makes the Pontiac G6, beyond 2013. But it says both parties will evaluate opportunities for future products. And the document says GM plans to transfer the Saturn Sky and Pontiac Solstice roadster production from Wilmington, Del., to Bowling Green, Ky., after 2011.

"No future product allocation has been identified beyond the life of the current agreement," the document says of Wilmington.

Messages seeking comment were left for UAW spokesman Roger Kerson and GM spokeswoman Katie McBride. In the past, GM has refused to comment on the agreement until the ratification vote is complete.

"This isn't a very genuine job security agreement," Shotwell said. "The UAW didn't win anything. The plants that are allowed to stay operating were already allowed to stay open."

Union leaders at other factories that received new products disagreed with Shotwell's assessment.

Dave Green, president of one of two locals in Lordstown, Ohio, said his plant got a commitment to build a new generation of GM small cars out of the deal. The company previously would not say what would be built at the plant near Cleveland after its current products, the Chevrolet Cobalt and Pontiac G5, go out of production at the end of the 2009 model year.

GM and the UAW reached agreement on the contract last week after a two-day nationwide strike.

The UAW was seeking to protect jobs and slow its falling membership in this contract, and President Ron Gettelfinger said GM responded with "unprecedented product guarantees." GM committed to building current or existing products at 16 of its 18 U.S. assembly plants, according to the UAW's summary of the contract.

The deal was endorsed Friday by local union leaders. It also requires GM to pay out at least $35 billion to the union to set up a trust to handle retiree health care and establishes lower wages for thousands of new employees.