The 2007 GMC Sierra Classic 2500HD goes out in pretty much the same way it arrived. GMC basically took an older model and slapped the classic tag on it, hoping to get some extra mileage before making way for the new Sierras. The three-quarter ton pickup truck comes in Regular, Extended, and Crew Cab models. 46 different trims make it almost certain you'll find a truck to your liking. As for the specs, the Sierra Classic 2500HD uses a 6.0 L, 300 hp V8 engine with 4 speed automatic, 5 speed manual, or 6 speed automatic transmission. Regular cabs have 2 doors and seat 3 while the Extended and Crew cabs have 4 doors and seat 5-6. If you need more power, you'll also have the option to upgrade to an 8.1 L, 330 hp or a 6.6 L, 360 hp V8 engine. Overall, reviewers like the powerful engine and available options. On the other hand, drivers agree that GMC has a reason for labelling this model a 'Classic.' The Sierra Classic 2500HD lacks quality materials and some basic safety features. If you feel the need to pay tribute to an old standby, this model has the power to pull you through some tough road conditions. For a smoother, more modern ride, stick with the new generation of GMC's.