I’ve been looking around a while and I’m not exactly sure what gears will fit the rear carrier I have.
Spinning the tires and counting driveshaft rotation looks like 2.78 gears and it definitely has anti-slip carrier as it has the anti-slip tag and both tires spin every time you nail the happy pedal.
When I look at Richmond gears, they claim their gears only fit 3.08 & 3.23 carriers. Anyone know of a source for 3.23 or 3.42 gears to fit my posi 12 bolt O rearend?

 

https://classicoldsmobile.com/forums...t-works-86138/

read post #9, maybe he can help.

 

Only thing you can do is make a RING GEAR spacer for the 12 OLDS carrier and then you can install the 3.42 or 3.90 aftermaket gears and ot GM 3.08 or 3.23 gears.
THERE ARE NO AFTERMARKET 3.08 or 3.23 gear sets. Period.

 

With no changes to anything, 2.56 and 2.78 gears will fit your existing 673 carrier. Change the carrier and you can put any of the ratios below in the rearend, assuming you can find the gears.

Here's some info that Brian Trick posted a long time ago:

Here is a list of the posi units & what gears they will fit:

#673 = 2.56 & 2.78 ratios, 28 spline
#671 = 3.08 & 3.23 ratios, 28 spline
#588 = 3.42 & anything numerically higher, 28 spline
#672 = 3.42 & anything numerically higher, 31 spline
***The 31 spline axles were offered in late 67-68 OAI cars only.

 

Thanks!
I don’t suppose anyone has these spacers figured out and are available?
In my simple mind it should be as easy as measuring between the mounting surface and the bottom of the ring groove and having a spacer made the difference between the two ring gears. Shimming the carrier and or pinion would hopefully get you within tolerance after the spacer install.

 

Thanks for the info. Very helpful

 

JD is helping out with the spacer and Summit had 7 sets of 3.42 gears when I ordered mine.
Whenever the weather stabilizes here in the next few weeks, I’ll get the car out of storage and swap out the gears.
Thanks for all the help fellows.

 

Well that surprised me. I wouldn't have thought Summit had them in stock. Good luck with it!

 

You guys had me nervous about finding gears. I had a set of 3.42’s in my cart since last fall but hadn’t figured out why my carrier wouldn’t work until now. The gears I had saved are the correct ones using my carrier with JD’s spacer. It specifically says for 3.08 and 3.23 originally equipped.

 

Yes, the Richmond Gear (and maybe all of aftermarket gears?) are made to fit that series carrier, for whatever reason.

 

Another question fellows; the Richmond gears I bought has a 27 spline pinion. Looking around at install kits I see they offer 27 and 28/30 spline install kits for a ‘69. Of course I’m going to order a 27 spline install kit but I don’t remember reading which spline comes stock in my car. Anyone know off hand what the stock spline count is?

edit:
I looked at Supercars and seen all were 27 spline. Not sure why Summit is offering a 28/30 pinion spline kit for a ‘69?

 

They probably have listings for the correct O- Type as well as 8.2” 10 bolt rears and 12 bolt Chevy rears.