the easiest way to make a 7.5 last when racing (AND YOUR U-JOINTS) is to load up the rear end, and not shock it. i broke two drivers side axles in two launches with my standard camino. there really isnt any way to beef them up except aftermarket axles, but i was reading about cryogenic freezing of racing parts that is supposed to make your parts twice as strong BUT its probably more expensive than just buying an 8.5 for your car. i eventually bought an 8.5 from a friend that is out of (i think) a
caprice. the lower control arm mounts and spring perches had to be moved but its cheaper than buying a Gbody 8.5. the only problem is that it sticks out 1.5" on both sides. but whats it matter when you can launch your car as hard as you want? lol
if you have to keep your 7.5 for budgetary reasons OR you have faith in it, just stock up on spare internal parts, and dont waste time on the locker rear ends cause when the spring or the little gear breaks in them you are screwed cause they arent repairable.