2003 Sierra with 8.1 liter 345 HP and Alison Auto. Plenty of power for towing. A little hestitant on take off when cold. 20,000 miles in 6 months and it runs like day 1. Fuel mileage is absolutely HORRENDOUS!!!! Towing an enclosed race car trailer x-country avg. mileage = 7.95. Driving enmpty no load at all avg. mileage = 12.98.
The Isuzu engine is the best part of this truck, along with the Allison tranny. The worst part has been all the GM stuff. Everything from numerous AC problems to leaks, memory features deleting themselves, multiple transfer case problems for auto 4WD, and leaking fuel injectors. If it were not for the dealership's attitude and incompetance i would buy again.
I bought this truck as a replacement for my 96' 1500 as I needed more muscle to tow a 5th wheel trailer. The 8.1L has plenty of punch, but I struggled with traction on anything less than dry hard surfaces. I have already experienced the typical Chevy/GMC parking light burn out on one side that they can't seem to fix and I have had numerous fuel indicator malfunctions. The fuel consumption is killing me and towing or not is not much difference. Ready to look for an older/smaller model again!