Gear ratio, RPO code

[Lokix27x]

Ok, I looked up my RPO codes to find out what gear ratio I have, come to find out I have RPO code GT4: 3.73 gear ratio, happy with that, then it says"DUP with 5 x 1" what does that mean? I've read all over people saying DUP means duplicate, that has to be false, there is no 5X1 code. And if you look through more codes with the DUP, some of their "duplicate" codes aren't there as well. I just want to know what the 5 x 1 means, and I also have the G80 code, other than opening diff, how do I know if it has locker? Or just limited slip...? Thanks guys.

 

[BlkYukon]

G80 means automatic locking rear differential - there is no limited slip as far as I know on the late model trucks (except for some Quadrasteer models but that's neither here nor there). Either a locking diff or open diff. That code has nothing to do with your gear ratio.

GT4 is the 3.73 gear ratio. DUP (duplicated) means there's another code (5X1) that was also used for 3.73 gears, but they no longer use it

 

[Lokix27x]

Thanks. Finally, a logical explanation to the 5x1.... and I knew the G80 had nothing to do with ratio, it's either a locker or limited slip, I've read that in multiple places. But I remember when I first got the truck I wanted to see if it would grab posi, so I did a burnout and it only did a one wheel peel...