looked up all rpo codes cant find the one for the diff anyone know what they are found the gear but no diff

 

i have a g80, and it's semi famous/infamous so it was easy to spot...
you may have to just write them down and decode away.
if you have "g80" then you have the G80 locking rear diff if it's anything else (open) i dunno what it is...

 

Your gear ratio will be a "G" something. GU6 is a real common one. It's for a 3.42 rear end. I see what you're saying thoigh. You want to know what rear end you have not just the ratio. Well... check this out. You are now hooked up.
http://www.c2e.info/rpocodes/gmrpocodesGthroughM.html

 

I think he is asking about the rear axle size. Most s-series trucks came with the 7.625" Corp 10-bolt & 28 spline count axles.

 

OK> Someone had a post not too long ago rhat dhowed all available rear ends complete with descriptioms and pictures.