"I think we have the best momentum we've had," said GM vice president Gerald Knechtel, the automaker's lead negotiator as an independent arbitrator wrapped up four days of hearings on the legality of the crippling walkouts by United Auto Workers.

The developments came after GM agreed to put metal stamping dies back into the Flint Metal Centre, and the UAW said it would allow up to 160 workers back into the facility on Sunday to install and repair the machinery. GM, which had secretly removed the dies in late May, agreed June 11 to return them but had not yet done so.

The dies are used to stamp hoods, fenders and other parts for GM's new full-size pickup truck, a crucial product being launched this summer. GM's action infuriated UAW members andtriggered a strike by 3,400 UAW members at the plant on June 5. Another 5,800 workers at the Delphi East instrument panel, spark plug and filter plant walked off the job on June 11. UAW vice president Richard Shoemaker said production would not resume at the plant until the strikes are settled.