I have an 89 RS. I just had an eaton posi and 3.73's put in and of course the pinion seal was replaced during the overhaul. A week goes by and the diff is leaking. So i took it back to my good friend who is the mechanic and he said, it proally need's a speedy sleve, so he put one on and of couse a new seal. I drove it for another two weeks and put her down for the winter in the garage. I got it on jack stands and went to take the shocks out and i looked at the diff and it is leaking. I am like what the heck!!! i am lost!!! i dont know if the seals were just not quality seals or what. but after a week and the speedy sleve it is still leaking. I think i should put another seal in and see what happens. I cant lie, i am very automotive with everything else but when it comes to rear ends i leave that to my friend. I am scared to do a pinion seal because i herd during the re assembly that if you tighten the nut too much you can crush the crush sleve more and cause bearing problems. Can sombody give me help on the whole situation please??? or walk me through the pinion seal replacement???

 

are you sure it's the seal leaking, there's also a fill plug, vent, and cover gasket. if it is the seal i measure the distance from the end of the pinion to the nut with a depth rod on a dial caliper and make a match mark. then R&R the seal, make sure you put lube on it, if you install it dry there's a good chance it'll burn up . reinstall the nut to the depth and match mark then go a bit more, like 1/8 of a turn.