I went to the dealer yesterday to have them pull info on my car based on my VIN number. I obviously have a M6 with 3.42's, but next to the G80 code, all it says is "limited slip differential". My buddy has a 99 Z28 and he has the same G80, and when we opened his rear up to change gears, we saw it was a Torsen due to the absence of clutches. My car is a 98, so I am guessing mine has the Torsen too?

Which one is the "upgraded" rear end, the Auburn or the Torsen? There seems to be some discrepancy with that. My buddy said the Torsen was the upgraded version, the dealer said the Auburn was.

So does the G80 code really stand for either Torsen or Auburn?

Also...the guy told me that you have to used the GM Additive on both the Auburn and the Torsen, I read somewhere here in one of the stickies that it's only required on the Auburn. He went on by saying that when he switched gears in his Torsen, he forgot the additive and the gears started howling right away, but after he added the additive it went away. Lastly he said that he uses two bottles of the additive instead of one?

Yeah....tad confused here....

 

98 was Auburn, 99 and up are Torsen. G80 doesn't tell the "type". My owners manual says to use the additive with LSD G80, although most newer synthetic gear oils say you don't have to use it - I do just to be sure when I change mine. One 4oz bottle of additive is plenty.

 

Ah well, I'll find out for sure once we put the new gears in...not that it matters which is in there, I am just trying to figure out what came in which year car. I thought I heard that the 98s came with Auburns standard and that the Torsen was optional.