HighFlyinZ

I just get a call from my dad that the rear end in the Camaro is going out. He says its drivable but has some 'Not so good signs of going out" My question is this. Where can I get a complete rear end, and I cant afford a 12 bolt as much as I would like to. Also while its open I want to go ahead and put 3.73's or 4.10's in but am affraid if I go with 4.10's I may end up doing it all again. - I probably wont put Slicks on it anytime soon but will a good Launch w/ the M6 hurt it pretty bad?