My '68 Cutlass has a 12 bolt Olds type rear .
I ordered a Powertrax for it from Summit Racing . The one they sent is for a 30 spline Chevy 12 bolt . And they don't know which one to send , and say only a 10 bolt was used in Olds . They are going to call Richmond Gear tomorrow , but I'm looking for a heads up first .
I thought a 12 bolt was a 12 bolt , but after reading through some post here , I find that maybe this is a one year rig .
Does anyone know which Powertrax is the correct for my car .
I had hoped to get it done this week end along with a disc brake conversion , but CPP didn't put the spacers for the axle in the kit .

 

Welcome to the site Frank. I don't know if there is a powertrax that will fit the Olds type O rear end. But that rear end was used from 1967-70 with both 28 and 31 spline axles. I know a member here was having new carriers cast, and here's a link to that thread:

https://classicoldsmobile.com/forums...unit-sale.html

Both monzaz (Jim) and 507OLDS (Brian) buy/sell/trade rear ends, used/rebuilt/and new. I would encourage you to verify if your rear end has the 28 or 31 spline axles, then contact these two guys and see what they say. If the Powertrax has a model that will work they will know. They may also be able to give you more information on what's available in your application. Good Luck! John

 

Thanks ,
and Its a 28 spline and 2.78 ratio I think

 

i seem to recall a recent post where Brian posted the part # for the proper powertrax unit. the ''O'' type rear end has a 12 bolt cover but only has 10 ring gear bolts. the main thing to emphasize to them is that it is the type "O" rear end with 28 spline axles...

 

You want the 1920LR.They make that for the 8.5" 10-bolt,but it will also fit the 12-bolt O-axle.