Well, here we go with the rear end swap.

The 8-1/4 is a pretty good rear for a c-clip axle. They consume a lot less power than an 8-3/4 (actually not a whole lot more than the 7-1/4) and stand up to a pretty fair amount of abuse before breaking. The only times I have actually known of them breaking has been in lifted big tired four wheel drives doing things they were never intended to do. The weakest part is the spider gears and carrier followed by the pinion (usually crush sleeve related).