Our spy photographers have caught an early mule of the U.S.-spec 2014 Chevrolet Colorado. The crew-cab truck largely resembles the global Colorado that just went on sale, though as GM said, there are some changes for the U.S. market. As far as we can tell from this mule, cosmetic variations will be limited to a more upright and rectangular front-end to better match the rest of GM's truck lineup.

Additionally, we can see what appears to be a front skid plate, indicating along with the ride heigh that the mule found testing could be a four-wheel-drive model. The frame rails look to be substantial, indicating GM is serious about taking on the class best-seller Toyota Tacoma with its 6500-lb towing capacity. The current Colorado tops out at 6000 when fitted with the optional 5.3-liter, 300-hp V-8.

One area where change is certain to happen for the U.S. market is the engine lineup. The global Colorado is offered with two four-cylinder turbodiesel options, but the traditionally diesel-averse U.S. market will likely get four- and six-cylinder gasoline options, though converging global emissions standards could facilitate the federalization of a diesel option for the U.S. model (perhaps a modified version of the 2.0-liter turbo-four slated for the upcoming Chevrolet Cruze Diesel), something not offered in a small Chevrolet truck since the discontinuation of the Isuzu-powered S-10 diesel in 1985. Of the gasoline engines, the most likely candidates are the just-introduced 2.5-liter I-4 and some version of the familiar 3.6-liter "high-feature" V-6. Additionally, our source indicates that a turbocharged 2.0-liter I-4 could also an option.

Although the future of the modestly-selling GMC Canyon variant has been in question, our source indicates that GMC will likely get a version as well and that the styling will be differentiated substantially from that of the Chevrolet. There is also some speculation, courtesy of GM North America president Mark Reuss, that the truck could also get a different name before it goes on sale in the U.S. For instance, the global model is sold in Brazil as the S-10.

Expected to arrive either in late 2013 or early in 2014, the U.S.-spec version of the Colorado (or whatever it ends up being called) will be built at the company's Wentzville, Missouri plant that currently produces the Chevrolet Express and GMC Savana fullsize vans. GM is investing $380 million in the facility in preparation for production of the midsize truck.