What gear oil in the diff?

[slant6billy]

OK 75W- 90
or 80W 90

or 75 - 140?

And if I use synthetic, do I still need to Sure grip limited slip additive part No4318060AC-M?

 

[rcmaniac791]

If I recall correctly, I think it's 80 90.

 

[80mirada]

And you still need limited slip additive unless you buy the lube that is marked for limited slip