Without getting into a Ford/Chevy/Dodge battle,
We had a n 04 2500 HD Chevy Crew Cab, 4X4 with the 6.0 and 4.10 gears
Pulled a 10K bumper pull around OK, but not good. 3 to 4 MPG pulling fully loaded and in 2nd gear at 4500 RPM most of the time if the road was anything but flat or down hill.
On vacation without toys and water (-2,500 #'s) she got 8-10 MPG and was happy with that load.
Now pulling the same setup with a 08 GMC D-max, Crew Cab, 4X4 and 3.73 gears she gets 8-10 pulling the full load, 10-12 without the toys and water and 16-18 MPG not towing.
The gasser never overheated or broke down and always got the job done, but I was just not comfortable with working the truck that hard. I tried a tuner on the gasser and played with the program and shift points and never could get any better performance from Her.
My opinion, not enough truck for the rig you wish to pull
2008 GMC 2500HD 4X4 DMAX CC
2004 Thor Wanderer Wagon 247WTB
2006 TE450 Husky
2007 Rhino Sport Edition