Look quickly, and you'll miss the changes, but GM's got some subtle exterior tweaks in store for its Heavy Duty trucks in 2010. Development doesn't stop even though the practice of using a pickup truck as a commuter car is no longer popular, so GM is plugging away at a new Silverado to avoid being passed up by its competitors.

Competition aside, there's also the issue of federal regulations to comply with, so changes were necessary no matter what. Most noticeably, the bumper changes, gaining a strip of trim that extends across the top, doing away with the overemphasized corner look of the current cow catcher. Looking more closely at the bumper, the air intake in the middle appears to have grown in size. That opening feeds the transmission cooler, so the speculation is that the Allison transmission has picked up extra ratios. Of course, it could just be bigger to gain an edge on thermal management underhood, but we're going to jump on the bandwagon of being excited for more cogs spun by the heavily revised 6.6-liter Duramax diesel with urea injection. That'd be just the thing to tow the Alero.

[Source: PickupTrucks.com, Photo: Priddy]