Also make sure you have some motor spray/brake cleaner to clean the grease off the parts along with diff lube (PN 6591) and black grease (PN 6588).

I would also replace the gears while you have it apart (PN 3914), they're only $6 or so.

Take a good close look at your balls to ensure they haven't worn out. I always replace them when I rebuild my diff. I rebuild mine about twice a year, although I don't get a lot of track time in (once per week if I'm lucky).