FACTBOX: Five facts about GM-UAW labor talks

DETROIT (Reuters) - General Motors Corp and the United Auto Workers union were working on Sunday to clinch a watershed labor contract expected to provide a framework for still-pending talks with Ford Motor Co and Chrysler LLC.

Here are five facts about the negotiations between the largest U.S. automaker and its major industrial union:

* The UAW's past contract with the three Detroit-based automakers covering 180,681 workers and 419,621 retirees expired on September 14. The union granted GM an hour-to-hour contract extension while marathon bargaining continues.

* GM and the UAW have been discussing a historic deal that would shift the automaker's obligation for more than $50 billion of retiree health care to a trust fund aligned with the union. The UAW has also asked for assurances that GM will not shift more production outside the United States to lower-cost economies such as Mexico.

* A tentative agreement would have to be ratified by a majority of GM's 73,454 UAW-represented workers. Ford and Chrysler have both indicated they are seeking similar deals to cut health care costs by transferring liabilities to newly created trust funds.

* GM, which has posted a combined loss of $12.3 billion over the past two years, already cut its factory payroll by more than 34,000 and plans to shutter 12 plants by 2008. GM's U.S. market share, which reached 46 percent in 1978, had plunged to 24 percent by 2006.

* The average GM worker made $39.68 per hour in 2006 with benefits including health insurance representing another $33.58 per hour. U.S. automakers argue escalating health care costs amount to a labor cost disadvantage of almost $30 per hour on average against Japanese rivals led by Toyota Motor Corp.

(Reporting by Kevin Krolicki)