I have access to this carrier at a local yard.

Are they rare or desirable with Big olds guys?

Is the carrier the same as the pontiac bigs in a 70 bonneville?

What can you tell me about these? WIW?? to sell?
Thanks

 

Those are what I call the large 12-bolts. It's a 12-bolt cover,with a 12-bolt ring gear,but the guts inside are larger than a 12-bolt chevy,and will not interchange.It's a nice piece for someone with a fullsize car,wanting to have a posi.

 

The rear pictured is a 12 bolt 'O' type FULL SIZE (12 bolt roaund symetrical cover and 12 bolts holding the ring gear in place) - They were used in the 1967-1976 Full size Olds. in 1971 -1976 all the big block FULL SIZE cars received this rear and the FULL SIZE wagons with BIG BLOCK MOTORS
31 spline bolt in axles (olds posi picture 1)

DO NOT confuse the A-bolt 'O' type 12 bolt (cutlass, 442) This rear has 12 bolt cover and 10 bolt guts)

The 1970 Bonneville and the 65 66 67 68 69 for that matter use the 8.875 FULL SIZE Pontiac 10 bolt cover 12 bolt ring gear rear. Rear cover and posi picture 2 and 3)

AGAIN the 10 bolt cover / 12 bolt ring PONTIAC FULL SIZE rear was used into the 1971-1977 Full Size cars and went from 31 spline to 28 spline and degraded from Bolt in axles to c-clip axles...

A-body GM cars had a optional 10 bolt cover 12 bolt gut 8.750 (derived from the older full size 10/12 rears) with a smaller 1.625 shaft (really the same as 10 bolt 8.5 shaft) They used a form of this axle assemble into the FULL SIZE caddies, olds, pontiac, etc. 1978-1984 85 ish That was as heavy duty as they had then... cars were not exactly putting out GOBS of HP in the late 70's and early 80's

 

Is this the 9.30" axle? If so, DTS sells parts:

http://www.drivetrainspecialists.com...ies/gm/gm-930/

 

I have a 12bolt cover on my car. I havent checked into it more than counting the bolts. I figured I would get to it when I was at that point, but I am now curious - what would a desirable rear end be out of the olds options? I dont know alot about this so if the question is naive i apologize.

 

It depends on what your definition of desirable is. If you're wanting to restore your car back to original, then the O type 12 bolt would be desirable if that's what your car was equipped with. The "down side" of the O type 12 bolt is that it wasn't produced in huge numbers, so there's limited aftermarket support (ie: lockers, gears, axles) and what is out there is comparatively more expensive. It's also said to be slightly weaker than its Chevy cousin, but this goes back to what you're wanting to do with it. Done correctly, any axle can handle a large amount of HP, including the O type 12 bolt. The other 12 bolt found in some Cutlass's is the Chevy 12 bolt (believe these were in cars built in Canada, not sure years) These units have a huge aftermarket following. Nearly every major manufacturer has gears, lockers, posi's, axles, disc brakes, etc.....This axle can handle a large amount of HP in stock form and can be built to handle extremely high HP and is used in a lot of fast cars. Overall, I would say the Chevy 12 bolt is more "desirable" but again, this is all based on preference and what you're trying to accomplish......

 

Joe, No DTS is selling the PONTIAC /OLDS third member parts (1957-1964). This rear end is nick named the GASSER rear. BIG and strong and back in the day it was what the PRO DRAG RACERS USED...

Not the same as the 9.3 Full Size mid 60's to mid 70's 12 bolt cover 12 bolt ring 1966-1976. Which is a integral housing.... Not a third member housing like the 1964 and older car rears.

The 12 bolt 'o type pictured on the first post was used in OLDSmobiles only until 1970 then in 1971 it became the one for heavy duty application in all the buick Olds and Pontiac FULL size BIG BLOCK cars and WAgons. The Buick 9.3 rear was dropped totally in 1971 and the PONTIAC 10 bolt cover 12 bolt ring gear was the intermediate heavy duty rear and the 8.5 was the new base rear for most all CARS...full size and A-body.

Hope this info helps some. I know it is confusing and that is why I am trying to help. Take care, Jim

J D

 

Don't be confused by this post. The OP is for a large car (B Body) diff. You have an A Body. Not the same animal.

Also, 12 bolt doesn't mean the number of bolts on the cover, it refers to the number of bolts that hold the ring gear to the carrier.

If you really want to do something for your car hook up with Brian or Jim (507 or Monzaz). Both of them are experts on rear ends and know their stuff. I've bought from Jim and am very happy with the posi he sold me. Mine now has 3:23 gears. Originally it was going to have 3:42's but that was before my 455 project cratered.

 

ditto I double that. I am answering the OP the first one full size car. Just to double confirm that ...If the other guy wants to start a post please do as it will get too confusing to discuss the B-body and a-body OLDS 12 bolts...lol.