I have a 03 savanna 2500 hd(3/4ton with 1ton springs) 5.3 gas engine, has always done the job set before it with no problems,and can squeeze 21 mpg with 2000 pounds on board. The only weak link is the Transmission, I've had mine rebuilt once at 180,000 and replaced with a reman. unit at 260,000 miles, I now have just under 400,000 on it and no signs of slowing down,