Whatsup, Im new here and I am about to buy a 2000 chevy tahoe limited from my cousins friend. Anyways the car seems fine but about a year ago he says the gaskets completely leaked all the oil onto the rear differential and he had to redo it, it cost him 2500 dollars. Well my dad says back in Italy, they always say that when the rear differential gets screwed up the car is never the same. My question is if you guys see any common future problems arising.

Welcome to AF
If done right it should be as good or better than new.
Good Luck