im running a 77 k5 that has 12bolt rear locked and 10bolt front open 1/2 ton. 4.56 gears. just a 350 nothing wilt just flat top pistons. mud only. i break stuff everytime i go. found set of these 3/4 ton axles for 300. how much better would they be than what i have now? what size tire will they handle? and again mudd only!