Pulled my fifth wheel trailer from Central Oregon to Williamsburg Va. and back {7200 miles round trip} my wife our 90 pound lab . The trailer weighs in at about 12,000# wet weight. Of course being aware that a possbile break down could happen with the truck or trailer was always on my mind. The truck performed flawlessly except when I would try to give it more go pedal on a steep grade. It would slip the clutch and a grumbling sound would come out of the right front area of the engine compartment. Don't know if it was from the Jake brake or not. The only other problem was the bedroom slide out it would not go back out. So we had to climb over the bed to get any thing we needed out of the closet for the last half of our journey. Got home and traced the slide out problem to a relay circuit board {loose solder joint} fixed that issue. Still baffled about the grumbling sound under the hood. Oh yah, also the truck would "hic-up" at times after a slow down and then a speed up. Like after getting onto an interstate after fueling up. Can't complain too much the Cummins engine ran great what a horse!!