I am installing a 1983 LSD differential in my 1979 SA.
The FSM does not show anything for the LSD because they did not come out till 1981.
I have heard that synthetic may not be the best gear lube for the LSD due to being too slippery.
I think a standard 75W-90 GL-5 with friction modifier or labeled for LSD should work.
I have seen a few that are marked for use in both open and LSD rear axles. This seems strange to me. I thought that the open rear would take an EP gear lube while the LSD would need no EP additive due to the clutches. Has the technology changed while I wasn't looking?
Any recommendations for gear lube?
Also what is the best RTV for the pumpkin to housing joint and best threadlock for the various bolts? (Driveshaft, center section, etc)
Direct email preferred since I am on digest.
TIA

 

I use copper silicone for the 3rd member and the german moly-lube for gear oil along with GM additive. However, any 75-90 synthethic gear oil will work fine.

 

I used Ultra Copper RTV that seems to work. (no leaks)
The Locktite RED (high strength) I used on the pumpkin and the u joint flange bolts seems OK.
I used Valvoline 75W-90 (labled for use in LSD) in the differential and I get a bit of chatter on tight turns, such as entering/leaving the grid at the autocross.
Seems like I need to find an Additive.
What would it be called and is there a brand name to look for? Where would I buy this additive?
The good news is it produces a bit more forward motion coming out of turns instead of spinning the inside rear tire!!

 

LSD additive can be purchased at any chevy dealer.

 

I just did mines
I to have an 83 and used 75w 90 and any auto parts store sell LSD additive.

 

I picked up a 4 oz. tube of Sta-Lube "Equa-Torque" LSD additive. Should get it in tomorrow but will not know how it works until the next autocross on May 20th.

 

I used Amsoil 80w90 if i recall properly. Its supposebly the better one for less wear and stuff.

 

I did mine yesterday. I used Mobil 1 75w90 and some Posi-trac GM additive for LSD's.