if your adding the synthetic 75w90 (i think thats the weight) , no modifiers are required but if you dont use the synthetic and go with regular fluid then I think I read that you need to add the posi additive. However I just buy the GM stuff and use as is.

 

Synthetic vs. conventional doesn't matter as it'll say on the bottle if it has friction modifier or not.

Not sure what you guys get up North, but here the Valvoline conventional and synthetic gear oils both have the LSD additive. Good to go either way regardless of weight, version.

The additive is not needed with the G80 though.

 

Bringing this old thread back.
The used diff I got is not a G80, it is a posi-trac / limited-slip diff out of a 70's Camaro, with the correct 7.625" ring gear and 28 axle splines....
I am sure it will fit, but now I am questioning what is going to be different in driving?
Just no experience with differentials except for equations.....

Comments....................

 

See above.