General Motors Corp. will close a parts plant and an assembly plant, and its former in-house parts operation Delphi Corp. will push to close or consolidate six plants under the tentative agreement reached with the UAW last week, the Detroit Free Press reported. Three of the affected plants are in Michigan, according to a UAW-produced summary. It says GM also wants to sell its diesel locomotive business and get rid of an office building in midtown Detroit near the automaker's former world headquarters. The summary says GM will commit about $1 billion in new business to Delphi at UAW plants. The commitment had been a late stumbling block in the GM-Delphi-UAW negotiations. Ford Motor Co. did not make a similar financial commitment to its former parts operations, Visteon Corp., in its tentative UAW contract. In return, the UAW and Delphi will meet within 90 days of contract ratification to discuss lower wages and less-generous benefits for new hires at Delphi. The world's largest auto supplier has struggled for new business because its plant-floor wages -- borne out of its GM-UAW heritage -- are much higher than many competitors'.