I used to tow a 35ft 10,000lb camper wiith my Hemi Power Wagon. The trick with the Hemi is to let it scream when towing. The more rpm's the better. It doesn't like to be lugged. I took it up Eisenhower Pass in Colorado with no problems towing the camper. The pass is 11,158 ft in elevation.
Madwi, if you are serious about getting a truck to tow. 3/4 ton or bigger. Everything is bigger on them. The thing about GM's. The 1/2 and 3/4 4x4's have the some front diff.
