I'm looking to change my front and rear differential fluid. And the transfer case fluid. But I have no G80 code in the glove box. I have been in the snow and mud many times to know that both tires do in fact lock up. Is there a way to check on the rear end itself if it is a G80? I know not to add and additives if it is a G80. But what kind of fluid would I use for the front dif and transfer case? 4 button 4wd. Thanks.

I have the GU6 code.

 

At low traction open diffs will spin both tires such as snow and mud. The real test is to get a burnout going on dry pavement and see if they both spin. If they both do spin then a previous owner may have done an lsd swap. And it wont hurt and open diff to put lsd additive fluid in it. Im running royal purple in my rear and front diffs and the transfer case.

And the gu6 code means u have 3.42 gears. Thats very common in the 4 door 4x4's