I just sold my 03 Avalanche, with a 5.3 engine 4 sp. It had 3.73's and I put in 4.10's. Trailer was a Gulfstream 25' loaded about 7k to 7.2k. I always towed in 3rd gear, in tow haul mode. Only drawback was the engine likes to rev. Keep it between 3-4K RPM's and you will be fine. I have towed to the Black Hills and to Yellowstone with nary an issue. I don't carry water and in MN we can't transport fire wood across county lines. I always kept my truck bed empty as my limitation was always the rear axel. I had room weight wise in the camper but made sure I packed most of the weight over the trailer axels. Have fun!