I have an 88 IROC with a 350 TPI and I'm wondering if someone would know what gear ratio it has in the rearend? I believe the rpo says GH3/680. I've been trying to go through the de-coder on thirdgen.org... but the site has been down. Thank you in advance to anyone who knows this!!

 

You either have 2.77s or 3.27s. 3.27s were a G92 option. See if your RPO list has G92 on it. It will also have the ratio on it, I think it's GU7 for 2.77s and GW6 for 3.27s. Might be GU5 for 3.27s, can't remember off hand. One of the two.

If you don't have G92, you have 2.77s plain and simple. Should be a 9-bolt Borg Warner posi.

 

What you have with 88 IROC 350TPI are:
RPO GH3= BW 9-bolt with a 2:77 gear ratio.
RPO G80= Limited Slip rear.
This was the most common set up every thing else was a extra cost option as G92= 3:27 ratio.

 

Thanks for the help guys!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

I found this list to be pretty helpful.