Quote Originally Posted by Ian R. View Post
At the time I could only buy enough RP for the transmission (the stores in my area did not have a lot in stock). So, I used Mobil 1 75w-90 gl-4. It cost something like 12.00$ a quart.
I think we are supposed to use hypoid 80w90 or straight 90w gear oil in the diffs. 75w90 is supposed to be for the tranny and transfer case only. Not sure if it makes a difference, but it might.

I think I will try the RP max gear as it is GL4/5 compatible and you had good results with it. Not sure what I will put in the diffs yet.