I'd like to install new seal/gear oil. What is a good sealant to use and what's proper gear oil I should be using? (how much of it?)

 

I used black rtv sealant by Permatex. I cleaned the edge with brake cleaner and applied a good 1/4" bead all the way around and around each bolt hole and let it skin over a little. A couple of blue stick pens cut in half and stuck in two bolt holes will help guide it straight on.

IIRC I used 85/90 Royal Purple for the front.

 

Do I have to add friction modifier to rear one?

 

Only if you have a limited slip differential.

 

Annnnnnnnd to find that out look in your glovebox

 

Synthetic gear oil states that it already has additive in it for limited slip differential. So I shouldn't have to worry about adding it separately?

 

I have run royal purple and lucas without any extra friction modifier, origianl LSD now has 230k on it and works good enough.