How can I tell (short of pulling off the diff. cover) if I have the G80. The G code in the glove compartment says I have a GT4, the window sticker make no mention of a limited slip diff.


Somewhere I read all 3500s come with the G80 as standard equip. What puzzles me is, it sure handles good on the snow and ice. If it does have the G80 why doesn't say so somewhere.


Thanks for any info.

Mark, whats your VIN?

GT4 indicates a 3.73 rear axle ratio, standard on all Duramax equipped trucks. G80 is actually the Regular Production Option code for the locking rear differential. There should be a white sticker, measuring about 3" X 5" in the glove box of your vehicle. Check there for all the RPO's on you vehicle. If you don't see G80 listed, you don't have the locker.