I am very impressed with this truck. It is the Duramax Diesel(LBZ 6.6l) with Allison Transmission. It's solid truck that drives extremely well. It is very quiet for a diesel. My kids actually fall asleep in it when we are on the highway because it is so smooth. Although, this truck has a lot of power! I like the body style but if I could change one thing it would be the tiny tires they put on this hulking truck. It really hurts the overall look of it and most buyers of this truck change them immediately anyways.
My favorite features are the Duramax and Allison. Together they are the best combination on the market
I would replace the tires for larger ones. I also did replace the stock head lamps for HIR lamps because the stock lamps are not very bright.