The 2014 GMC Sierra debuts in Pontiac, Mich., Thursday, Dec. 13, 2012. General Motors unveiled a new versions of its top-selling Chevrolet Silverado and GMC Sierra on Thursday Dec. 13,

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The 2014 GMC Sierra debuts in Pontiac, Mich., Thursday, Dec. 13, 2012. General Motors unveiled a new versions of its top-selling Chevrolet Silverado and GMC Sierra on Thursday Dec. 13, 2012. The 2014 models will go on sale by early spring or late summer. The models roll into a market where truck sales are growing after a five-year slump. (AP Photo/Paul Sancya) less