Mine is a 2001, crew cab, and the reason the GVWR is 6600 on mine is because of the 3:55 gears, If I go to 3:73 it will bring it up to 6850, and I just may do that. The Stock 5.4 is a good engine, I just have a bad habit of liking to play with things, the problem is the weakest link is the transmission and U Joints when you put a lot more power than they were designed for.
Do you run yours in overdrive on flat highways?
Terryallan; thanks your your input, obviously I have never used a WDH, it took me a little time to figure out how it worked, I probably spent ten minutes looking at one at the dealer until some nice guy explained the geometry and how it worked. One thing I noticed is the rear mounting bolt does not protrude through the frame, I was told so the thing could shift or move, that seems like it would defeat the purpose.