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I'm reading various things about early GM differential housings and series types.

I'm hoping some of you guys can clear some of this up for me.

I have a GM 10 bolt axle in my 67 Camaro. The gearset has a 1966 date stamped and is 3.08 gears. Axle type is PA.

I purchased a set of used 67 2.73 gears from a member here on FirstGens. These gears do not fit my axle.

I can't find any info online about the 10 bolt salisbury series axle except for here http://www.carcraft.com/projectbuild/ccrp_0608_10_bolt_bop_whats_your_problem/index.html.

On that article, they only speak of the 10 bolt for a brief period but further on say that the 2.x series gear ratio generally only works with the 2.x housing and the 3.x series generally only works for the 3.x gear housing and the same for the 4.x.

The reason I wanted to change the ratio from 3.08 to 2.73 was to compensate for the lower profile tires. That way I'd have an accurate speedo (I know can be fixed with a speedo gear) and slightly better fuel economy. I don't race the car...I simply just cruise with the wife and kids on the weekends.

yup, there ate 2 3 and 4 series carriers. That's just the guts, not the entire housing. The difference is where the ring gear flange is located, left to right on the differential.

As the ratio's change, the number of teeth and therefore the diameter of the pinion gear gets larger, forcing the ring gear to move over by getting thinner. There's only so thin to get though, so they make the 3 different carrier.

The difference between 2.73 and 3.08 is pretty small, you might just leave well enough alone and chenge the trans gear to make the speedo right. That's an easy and cheap swap.

You could always go buy a 2 series posi, but that's $500.
And setting up those gears is expoensive too unless you can do it yourself.

Yes...I can do it myself. I've done a couple with the help of my father.

I just put the 3.08 back in there for the time being.

The 2.73 pinion was considerably larger than the 3.08 gear which shifted the ring too far to the left (driver side). Because of this, I couldn't get the carrier assembly in place with the 2.73 gears.

yup, you're gonna need a 2 series carrier then. Bet you could find an open carrier used really cheap. posi's gonna be a different story tho.

Anyone know what the part # is on the Series 2 posi carrier would be? I may have one but then again it could be a Series 3...............part number will answer the question. If it is a Series 2 unit I will let it go real cheap if you are interested

If it's a 2 series and it would fit my axle, I'll buy it from you.

I'm thinking the axle is all the same as well as the housing, but the carrier is what's different.

If I put the 2.73 ring gear on my 3.08 carrier, it don't fit in the housing due to the 2.73 pinion size being larger.

I amm working on verifying whether the carrier I have is a Series 2 or 3. I know its not a 4 for sure. I'll let you know as soon as I can. Tom

Awesome! thanks.

I'm assuming that the carrier has to match the size of the rear end. I.E. an 8.2 carrier won't fit in an 8.5 rear. I hope for Lockport's sake that Tom has a 2 series to fit the rear he's got. I have a 2.56 posi in mine and I hear they're rare. I'm also told that a 4 series gear will fit on a 3 series carrier with a spacer, but it doesn't work the other way around.

I should have clarified this earlier.......is this the 8.5 10 bolt or the 8.2 we are talking about here? I just assumed it was an 8.5 but now that Jeff has brought it up I need to ask becasue what I have is for the 8.5.

This is the reply I got back from my contact at Quick Performance.....

"Tom-
The carrier break for the GM 8.5" rearend is 2.73 & Numerically higher and anything less then 2.73 and numerically lower. The 2.73 and numerically higher carrier would measure 1-11/16" from the table up to the surface where the ring gear sits. Let me know if you have any other questions.
Thanks,
BRYDON"

Based on his reply the 2.73 and 3.08 should work with the carrier you have. I will bring the unit I have to work tomorrow and put it on a granite surface plate so I can get a reasonbly accurate measurement to see how close mine is to Brydons suggested dimension and will let you know.