if its a superduty dana 50, then you could do better. as stated above, weird bolt pattern, ball joint knuckles, unit bearing hub, brake caliper slide pins like to seize. I dont know if I would call the gears weak tho. My truck weighs 8000lbs, on 35 BFG ATs, and I have done a LOT of 4x4, boosted launches at the drag strip and never hurt anything. I cant imagine a 4000lb wheeler can put much more stress on the gears than I have unless your spinning the tire in the air and then dropping it onto solid rock at high speed. But what drivetrain likes that?