I have the '03 1500 HD 4x4 with the 6.0 and 4:10 gears and it pulls my 22' Schiada like it's nothing. I don't have a need for anything more than that. As far as Chevy vs. Ford, my $.02 is that the Chevy has a far better engine, but the Ford has a far better ride. The rear end of my HD is like a f**king stage coach on the God Damned cement freeways we have around here.
Good luck with your decision.