Car Enthusiast

are the posi carriers different between a 2 and 3 series carrier? If they are are they swappable between the two if you swap out everything in a rear? Just trying to learn the differences between the two rears so I know what will work and what will not, and what will if I find certain parts

as you can get 3 series gears to work in a 2 series rear if you get a spacer? right?

Injuneer

The limited slip (posi) is a part of the carrier. Same posi components will work in both carriers. You can swap a complete 3-series carrier into a rear axle assembly that came with a 2-series carrier. They are interchangeable.

The main difference between the 2-series and 3-series carrier is how far away from the centerline of the pinion shaft the mounting surface for the ring gear is located. That's why the ring gears are not interchangeable. The thickness varies. If you want to keep the 2-series carrier, you can either buy a ring gear that is made to fit the 2-series carrier, or use a spacer to fill the gap if you run a 3-series ring gear. You will also need to address the location of the ABS reluctor gear (3-channel system only) when you swap carriers.

Car Enthusiast

Okay here is what my problem is:

As the car sits it has a set of 2.73's with a six speed that I am going to swap gears to a 3.73. So as the car sits as a 2 series I have trouble finding 2 series posi's and I find a bunch of 3 series limited slips. So it doesn't matter what kind of posi it is it will swap over, now is that just the carrier or will a complete rear fit into my differential casing?, keeping the axles the same and what not. And what is different between the abs reluctor gears between the two and three series rear ends

Car Enthusiast

just to simplify what I would like to do:

I could take out my 2.73 worn out auburn posi/gear unit and put in a 3.73/eaton posi/gear unit and it would work?

Capn Pete

Whoa! That's something I've never put any thought into before!

Is the sensor definitely moved over left or right depending on which carrier it was intended for? Huh, and here I would have assumed it was "centrally located" and you could go about swapping the carrier inside all day long with no negative effect!! I guess that's what I get for ASSuming?

PoorMan

When I swapped 2 to 3 series I did not know about the different reluctor rings. I am running a 2 series ring with my 3 series carrier now. Car runs fine just no ABS (light is on). I bought a 3 series ring from SLP for $20 just have not installed it yet.

Injuneer

A "posi" is a "limited slip". Its short for Posi-traction, which was Chevrolet's trademark for a limited slip differential. Pontiac called it Saf-T-Track.... all the same thing.


The "carrier" includes the posi. You buy a complete 3-series carrier, with the posi, and it bolts right into the stock housing. The carrier without a limited slip just has spider gears and cross-shafts inside. The Posi (at least the clutch type, not the Torsen) adds a set of clutch discs and springs that connect the two spider gears together, and "lock up" when the rear axle is under load and one wheel starts to slip. Buy a complete 3-series Eaton carrier/posi unit. There was a good article in High Performance Pontiac last year, that included the Eaton part #. Try a "Search".... I know others and I have posted the link.



That's an Eaton out of a 12-bolt, but they all look the same.

Car Enthusiast

cool, that helps in with searching for a posi unit.

Is there any difference in the abs reluctor ring?