See sig, no problems pulling, is much improved over my 02 2500 with the 6.0 and 4 speed. I tow around 10k and have no issues. The best part is the drivetrain is so reliable, GM has really built a great LS engine series. Having pulled with both gas and diesel, I stayed with gas. Easy to maintain by myself and cheap to fix. The newer diesels are really nice, problem is that my wallet just won't handle a repair bill when something breaks. I can tell u that the GM 6.0 won't let u down, it will pull grades and will run 4 th or even 3 rd gear doing it but will keep the speed. Hope this helps and other 6.0 owners chime in.