Bought this as a replacement for my 2001 crew cab duramax. I was a little worried about if it would be able to tow my 12000 lb trailer since it has the 6 liter gas engine. As it turned out it has no problem whatever towing it and the 6sp allison tranny is a joy. The mileage could be a little better but since regular gas is alot cheaper here than diesel it works out alright. I especially like the built in trailer braking system instead of having the aftermarket unit hanging under the dash. After 20000 miles I have not had a single problem with this truck . It is as tight and quiet as the day I bought it. I only use it for towing our 35 ft camper. Again love this truck.