Hello,

Not sure what I have here. This axle is in a 442.

10 bolt posi 2.78:1 ratio. 55.75" backing plate flange to backing plate flange. It has 8 bolts that hold the carrier halves together. It had the red tag for limited slip additive and the LS tag on the cover bolt before I blasted it.

Everything I find says it's a "P" 10 bolt from a 67' earlier but it's wider than those. Everything I find says the 442's came with a 12 bolt. Did any of them ever come with a 10 bolt?

Thanks for any help.

 

I think 1967 went 1 inch wider than 1966. Post a picture of the cover. Does it have bolt in axles? If C-clips it could be an 8.2, 10 bolt cover from like a 1968 Chevelle.

 

Bolt in axles.

Chrome cover that has had the top and bottom bolt holes filed slightly larger.

 

Only the Canadian-built 442s came with a true "12 bolt" Chevy style axle in 1968. All the US-built cars came with the Type O axle that had a 10 bolt ring gear but a 12 bolt cover. In any case, this 10-bold cover axle is not original to the car. How big is the ring gear? Could this be a 1971-72 "corporate" 10-bolt axle? The Olds versions had bolt-in axles.

 

The corporate 1971/72 10 bolt 8.5 had a similar "slash" but on a factory cover plus bolt in axles.

 

1969 Pontiac Tempest 10 bolt.

9799100 casting # fits GTO/lemans with 10 bolt
I found XC stamp. "X"= Posi "C" = 2.78

Thanks for the help. I don't embrace technology that much but it sure comes in handy sometimes.

Now what to do. I was hoping for a 12 bolt. I do have a 8.6 with fresh 3.73 and Eaton posi from my days in the lab at Eaton. I'd have to get some brackets and weld them onto the tubes. I stripped them years ago when the plan was to put in a chevelle.

 

Yep, the split case is the giveaway on those. FYI, my brother-in-law had one in his 68 GTO (3.55 gears) and it held up through a LOT of street abuse over several decades.

 

Well it really all depends on how much money your going to plant into the rear.
IF your going to just drive it and have fun burn outs and go to the track with street tires YOU will be fine.
IF your going to put gears posi bearings etc. and put drag slicks on and a stick shift car you might want to start with a better base.
The pontiac rears I consider a VERY good rear...The caps are the largest of all 10 bolt rears. Even the 10 bolt 8.5. 8.2 caps are wider and thicker for better carrier stability.
Aftermarket gears will always strengthen a rears power handling capability.
Posi unit is limited to 2.56 and 2.78 gearing so that will need a replacing also and again aftermarket hardened spiders will make the rear again stronger for more power handling.
In the world of WANT it may not be a 12 bolt ...but in all reality it will do the job for what you will probably do with the car - even 455 power on the street it will be fine. Just have to get someone build it correctly...THAT is always the key...engines transmissions etc.

Oh and the rear is a Pontiac 8.2 as stated and the cover is a aftermarket 8.5 / 8.2 chevy as you said the holes were drilled oblong to make it fit. traditionally that is the 10 bolt 8.5 Oldsmobile cover. 71 72 73 74 75

Jim
J D RAce

 

Thanks Jim.

We are going to leave it alone. New cover gasket, axle seals, wilwood brakes. This car will never see the track. I'll keep an eye out for a reasonable 12 bolt.

The 8.6 I have is out of a Caprice so the ears are in different locations. Too bad as I built it from scratch with new parts. I can narrow it and get new shafts but I don't want to weld ears onto a housing.

Putting one together properly for me is no problem. I installed 3-5 per day for eight years on test benches and vehicle testing.

 

We have custom upper control arms that might be about to bolt that caprice rear in...We make them for the G -body rears - they are fully double adjustable and have a spherical rod end for slight off angle like you will have. Picture is of the arms holding in a 90-96 caprice center into a g-body we modified the width and moved the lower control arm and upper spring perch mounts to correct g-body specs. They work very weld and most of all articulate correctly when you hit dips and holes in normal driving situations.
150.00 a pair