The big three American automobile manufacturers are headed into the shop for repairs after a bumpy fiscal year, as a foreign rival tops them all for the first time.

Late last week, The Wall Street Journal reported that new Ford (NYSE:F) President and CEO Alan Mulally was planning a radical revamping of the company, plans for which are expected to be unveiled during or soon after January's Detroit Auto Show. Mulally, who joined Ford in October from Boeing (NYSE:BA), reportedly has said in an email sent throughout the company that Ford currently is going through an "extraordinarily gut-wrenching time."

It now also appears that General Motors (NYSE:GM) and Ford will be pushed back a notch in the hierarchy of automobile manufacturers as Toyota (NYSE:TM), which has been steadily ascending for years, moves into the top spot. On Friday, Toyota said it expects to produce about 9.42 million vehicles in 2007, which would outstrip the 9.18 million vehicles that GM will likely produce this year. GM's 2007 production is projected to be flat with this year's at best.

Not to be left out, DaimlerChrysler (NYSE:DCX) apparently will unveil a restructuring plan of its own in February, when it releases its 2006 results on Valentine's Day. The company's plan is expected to include plant closings and job cuts, although the latter should be less draconian than the 40,000 employee layoffs that Chrysler endured in 2001. Earlier this year, both GM and Ford offered buyouts to their hourly workers, with 34,000 GM employees and 38,000 of their Ford counterparts accepting the offers.

However, in another respect, it's nearly business as usual at Ford. The company is in the midst of an estimated $80 million marketing campaign to push sales of its new Edge, a crossover vehicle with an SUV body built on a car-based platform. At the same time, the company has ended production of it Taurus sedan, a once-popular model that it produced almost unchanged for nearly 20 years. And late last week, the company announced that, in exchange for more than $150 million in tax incentives from the state, it would invest $1 billion in six southeastern Michigan plants.

But at the close of an extremely trying year, the hoods are effectively up at all three of the big U.S. auto manufacturers, and their respective managements are up to their elbows in corporate overhauls. While it appears reasonable to assume that one or more of the resulting restructurings will result in a brighter future for its associated U.S. auto company, I'd nevertheless urge Fools to adopt a wait-and-see attitude on potential investments in the Big Three.

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Fool contributor David Lee Smith does not own shares in any of the companies mentioned. He welcomes your comments or questions.