I pulled a 30 ft toy hauler with 373 gears and and 35's under the truck.. I have the edge also gibson exhaust k&n air intake... throttle body riser.. And now i just up graded my gears to 456's and now turning my 35's (BFG's) i have no trouble at all. and i'm well over 9 thousand lbs with that combo.. Truck just hit 8o k and i just did the gears... Hands down this truck was built from tuesday-thursday... Cause friday they didn't care and wanted to go home and monday they were still hung over.... I love this truck. You should have know problems pulling 6k. What gears and what size is your bed?

MArk