well gears and set up kit around 300 ish or more per axle, u bolts for the axles about 10 bucks each, dont know if the u joints are the same, but I know they make u joints to go from 1/2 ton to 3/4 ton axles so that not a problem (30 each) fluid about 6 quarts at least (5 bucks each) and thats saying all the bearings and seals brakes, ect are ready to roll. I mean you can do it no problem, but why go to a heavy axle and put the same gears in it? kinda like trimming a dead tree. your not going to brake the axles that are in there with stock size tires and good driving. But if you were to lift it and put some larger tires then go for it. But I would think that the weight of the larger axles would hinder the MPG's even with stock gearing (3.08's)