After some nervous moments in the last three weeks, representatives of the United Automobile Workers (UAW) union agreed to a new four-year labor contract with Chrysler, now owned by private capital group Cerberus Capital. The deal guarantees future work to much of Chrysler's workforce and hopefully puts to rest the October 10th six-hour walkout that's still fresh on the UAW's mind.

In reaching an agreement with Chrysler, the largest automotive union now can look forward to negotiating a deal with Ford Motor Co. (NYSE: F), as deals with General Motors (NYSE: GM) and Chrysler are now complete and in the books. The agreed-upon contract with Chrysler finally gained support at the plants that mattered, including the four larger Detroit-area car factories. Although some of the voting plants, such as a plant in Belvidere, Illinois, still had issues with the contract, the majority votes were enough to give it ratification as of late this weekend.

According to the UAW, roughly 56% of hourly workers and 51% of skilled trades workers approved the agreement as of this past Saturday evening. That's not a huge sweep of approval, but it was enough to put the negotiations to bed for the next four years.

At least for the next four years, Chrysler's union employees will have some sense of security as the automaker struggles to return to consistent positive performance under the ownership of a private set of investors. With Ford up next -- and obviously feeling pressure to mold a new agreement in the vein of the recent GM and Chrysler contracts -- the UAW still has its greatest test ahead.

The cornerstone of GM's (NYSE: GM) contract with the UAW is that the company will fund a health benefits pool run by the big union. The car giant will probably move $30 billion into the pool and will part with a $50 billion employee healthcare liability. In turn, GM will guarantee a certain number of jobs.

That deal may not work for Ford (NYSE: F) or for Chrysler for that matter. The No.2 US car maker needs expense relief now. Its sales keep falling, and were off over 20% in September. Bloomberg quotes one expert who sums up the issue nicely: ``Ford isn't interested in job guarantees'' as the company shrinks, said Gary Chaison, a labor professor at Clark University.

Ford's problems are acute. While it may want to get health and pension liabilities off of its balance sheet, it still needs to cut is North American costs by a large amount. GM's sales seem stable, but Ford's past focus on pick-ups and SUVs has put it in a bad spot. As fuel costs have risen, these vehicles have become less attractive. Without large cuts in workers, its North American operations could continue to lose billions of dollars a year.

The chances for a strike in Detroit are rising again. But, this time the target will probably be Ford.

Douglas A. McIntyre is a partner in 24/7 Wall Street.