Two top Ford Motor Co executives who helped steer the U.S. automaker through the financial crisis will retire by April 1, thinning the ranks of likely candidates to replace Chief Executive Alan Mulally in coming years.

For his part, the 66-year-old Mulally said, Our plan at Ford is to have a very strong succession plan for every position including my own, but that he had no plans to retire.

Chief Financial Officer Lewis Booth, whose exit was expected, and Derrick Kuzak, the product development chief whose departure was a surprise, will be replaced by long-time Ford executives.

With the exits, industry analysts and company insiders say the leading candidates to succeed Mulally are Mark Fields, 51, who runs Ford's operations in North and South America, and Joe Hinrichs, 45, head of Asia. Fields is widely seen as the favorite.

Mulally dismissed speculation Booth's departure would allow Ford to name Fields chief operating officer as a way to prepare him for the top spot. Mulally refused to say whether Fields and Hinrichs are the top candidates to be Ford's next CEO.

Guggenheim Securities analyst Matthew Stover sees Thursday's announcement as the first step in the succession process that is not likely to play out this year.

It means the clock has really started to tick and everybody's listening, he said. This is something that probably happens in the next couple years.

SUCCESSOR CRUCIAL

The next CEO is crucial to Ford because Mulally is so closely identified with the company's success and ability to avoid the federal bailouts that rescued its U.S. competitors General Motors and Chrysler .

During the first three years of Mulally's tenure, Ford lost $30 billion, but in the past three years it has shown a profit of $29.6 billion, including a one-time accounting change regarding deferred tax credits in 2011 of $12.4 billion.

Gary Bradshaw, portfolio manager at Hodges Capital Management in Dallas, which owns Ford shares, remains confident in Ford's executive talent.

They've got a good, deep bench there, he said. Nothing really will change.

Stover expects Ford to return to its historic pattern of tapping an insider as Mulally's successor. Mulally was hired from Boeing in the fall of 2006.

Both Booth, 63, and Kuzak, 60, have been with Ford for more than 30 years. Booth will be replaced by Vice President and Controller Bob Shanks, 59, and Kuzak will be replaced by Raj Nair, 47, the head of engineering for global product development. Shanks has been with Ford for 35 years and Nair has been with the company for 25 years.

Booth became CFO in 2008, a week after the collapse of Lehman Brothers investment bank. Kuzak has led Ford's product development since December 2006.

Both executives played key roles in Mulally's One Ford plan, a centerpiece of Ford's turnaround that calls for the automaker to unify its once-disconnected business units and take advantage of its scale to drive down costs and build a global brand.

Mulally cited Booth's contributions to straighten out Ford's balance sheet and reinstate the dividend after helping the company through the rocky financial times after it mortgaged assets. The British-born Booth also steered the automaker's sale of Swedish luxury brand Volvo to Chinese automaker Geely, and during his tenure the automaker cut debt.

Kuzak was charged with launching a series of globally developed and designed vehicles that left Ford with more new models when its U.S. competitors had thinner new offerings. Kuzak ushered in the global versions of the sedans Fiesta, Focus and most recently the Fusion.

Also on Thursday, Ford said former U.S. ambassador to China and one-time Republican presidential candidate Jon Huntsman, 51, will join the company's board. He joins a board that also includes a former Democratic presidential candidate, Dick Gephardt.

Ford shares on Thursday were down 0.6 percent at $12.76, and up about 19 percent since the start of the year.

(Additional reporting by Ben Klayman, editing by Dave Zimmerman)