Accoring to Edmunds.com: Powertrain choices, traditionally a strong point, encompass everything from a frugal 4.3-liter 195-horsepower V6 to a muscular 6.2-liter V8 with 403 hp. Most Sierras, however, will be fitted with either a 295-hp 4.8-liter V8 or a 315-hp 5.3-liter V8. A four-speed automatic is standard across the board (except for the Denali, which gets a six-speed unit) and one may choose either rear- or four-wheel drive. Don't the 4.8L numbers fool you, the 5.3L gets the best fuel milage of the buch, by a long shot. IF, you can keep your foot out of the gas. This truck will bull a house if needed.
The 2008 GMC Sierra-3500HD's engine produces 353 hp @ 5400 rpm.
The 2008 GMC Sierra-2500HD's engine produces 353 hp @ 5400 rpm.
The 2008 GMC Sierra-1500's engine produces 195 hp @ 4600 rpm.
The horsepower of a GMC Sierra is 355 hp.
270hp
295hp
285 horsepower
The 2008 GMC Sierra-2500HD's engine produces 373 ft-lbs. @ 4400 rpm.
The 2008 GMC Sierra-3500HD's engine produces 373 ft-lbs. @ 4400 rpm.
310 hp
somewhere around 200hp
315 horsepower stock