I just pulled the diff cover off of my 2002 Z28, 6spd with 3:42's and this is what lives in there. Is this a gov-loc? The code list on the door list a "G80" code.
I put the car up on jackstands and noticed that when one tire is rotated the other spins in the opposite direction.
I started the engine, put it in gear and was able to hold one tire still while the other was just spinning freely... (yea yea, I know) Is that normal? I thought it would "grab" if it was a gov-loc.

 

TORSEN. Toque Sensing, sort of a limited slip.

 

Ok, thanks... I will search for more info about it now that I know what it is.
I refilled the pumkin with 75w90 Royal Purple, I hope that was the right thing to do.