I was sold some Bel-Ray 80W-90 GL5 fluid from the dealer. Will this work for both the front and back? The owner's manual calls for SAE80 in the rear but Bel-Ray doesn't make it. Are they the same thing?

 

By the manual it calls for GL4 but had a dealer tell me GL5 was alright for both.

 

I would go with the GL5, it is rated for a limited-slip differential, which you have up front. You will also need to get some General Motors limited-slip additive, and put an ounce up front for the clutches in there, otherwise you will lose the grip of the front end some, and may notice some clicking or ratcheting noises from the posi clutch up front. I got some Amsoil gear lube, seems to hold up really good, and is rated for limited slip axles.