I have a factory posi unit out of a 8.5 rear from a 79 camaro. I have no idea if it's good or not. How hard are they to rebuild. I've read somewhere that if the clutches look good you can just shim them up. I also had to beat the &^% out of the cross shaft to get it out. It was pretty trashed. I just don't want to put this in a rear and have to pull it right back out.