Workers at five Ford Motor Co U.S. plants represented by the United Auto Workers have backed a contract aimed at bringing the automaker's labor costs in line with rivals General Motors Co and Chrysler.

These early returns come as the proposed changes to Ford's 2007 contract with the union could face a bigger pushback from the 41,000 Ford U.S. UAW workers who have made a series of givebacks to the automaker since 2005.

Workers at Ford's Michigan and Wayne assembly plants near Detroit voted to ratify the contract, said a source familiar with the process who was not authorized to speak because the ratification has not been completed.

At three Cleveland-area plants, workers backed the proposed contract changes 61 percent to 39 percent, UAW Local President Mike Gammella said. The local represents about 1,300 workers at two engine plants and a stamping plant.

Initially there was a lot of pushback, but once people heard the details they supported it, Gammella said of the
proposed changes. They weren't doing cartwheels over it, but they understood.

The turnout was more than 80 percent, Gammella said.

Other locals have scheduled votes through next week on the tentative agreement the UAW and Ford announced Oct. 13.Approval requires a majority of the votes cast by workers.

The proposed changes include a no-strike clause, wage freeze for entry-level workers and other concessions. Ford also made some production commitments and is offering a one-time $1,000 bonus next year if the automaker meets quality targets.

Ford's UAW-represented workers agreed to concessions earlier in 2009 the automaker said would save it about $500 million per year.

However, Ford said agreements GM and Chrysler made with the UAW around their government-supported reorganizations would put the company at a disadvantage over the long term and sought more cuts to bring costs in line with those rivals.

Ford shares were down 5 cents or 0.6 percent at $7.71 on the New York Stock Exchange on Friday afternoon.

(Reporting by David Bailey; Editing by Lisa Von Ahn and Matthew Lewis)