Never heard of a 12 bolt type O. Maybe it is this rear? 'O' type posi 'O' type posi U-bolts on yoke U-bolts on yoke Ssymmetrical 12 bolt cover Symmetrical 12 bolt cover 1/4 cut slugs bolt in axles 1/4 cut slugs bolt in axles Ring Gear Diameter 8.4 Olds Cover Bolt Count 12 Ring Gear Bolt Count 10 Ring Gear Bolt Size 7/16 right hand thread / aftermarket gears 7/16 left hand thread Axle Spline 28 bolt in axle 60 degree spline 31 bolt in axle (SPECIAL 67-68 SUPER DUTY OPTION) Pinion Spline 27 Yoke Style U Bolt & Nut Universal Joint retention (reference picture) Pinion Diameter 1.625 <<<< AFTERMARKET GEARS ARE AVAILABLE FOR 12 BOLT OLDS (For 3 series carrier only) Axle Shaft Diameter 1.382 press on bearing Supported Cars: Car Year 442 67-68 Cutlas 442 (USA ONLY) 69-70 Rebuild Kit Includes Part Part Number Carrier Bearing LM501349 Carrier Bearing (Race) LM501314 Inner Pinion Bearing M802048 Inner Pinion Bearing (Race) M802011 Outer Pinion Bearing 86649 Outer Pinion Bearing (Race) 86610 Pinion Seal 2043 Axle Bearing 67-68 SEALED BEARING RW507CR Axle seal 67-68 INNER TUBE SEAL 8594S Axle Bearing 69-70 OILED BEARING A9 Axle seal 69-70 EXTERNAL SEAL 712146 Mega Axle Bearing Kit: Source: www.jdrace.com
If the price is a really good, and the posi is tight, go for it. I think you need to get modify the length of your driveshaft if you still have 71 8.5 rear in it. Al
Larry, The type "O" 12 bolts are the Oldsmobile 12-bolts, not the Chevy 12 bolts. I have one in my 70 442. Duane
duane, isnt it pretty much a 12 bolt hybrid, as the center section is actually a 12bolt carrier w/ bolt-in 8.5 axles? or something to that extent
Mike, You're asking the wrong guy that question. All I know is I have a 70 Olds 12-bolt 3.23 posi in the car and picked up a 70 Olds 12-bolt 3.23 non posi for parts, and was later told nothing is interchangable. That's all I know and am not sure if that is correct info or not.o No: Duane
The "O" rear end is a 12 bolt cover, 10 bolts on the ring gear rear end. Only offered from 1968 thru 1970. Comes in both non posi and posi. There are 2 carriers: One from 3.23 and lower, and one from 3.42 and lower. Carrier parts do not interchange between the two. Aftermarket parts are limited.
The "O" type is an animal all to itself. Olds only, 12 bolt cover, 10 bolt ring gear. Virtually nothing in common with the 8.5s or the 12 bolt Chevy. Size wise I believe it would bolt right in. If its a functioning posi complete axle then go for it. If it requires work, build an 8.5 or a Chevy 12 bolt. Parts will be more readily available and cheaper.
I wish I had a 8.5 - I have a 69 3.42 posi that I can't get parts for:ball: The rear is suppose to be in good shape - complete - pictures looked good asking $750 This rear will be for a high 500 to 600 hp street car Should I wait for something else?
Just sold one of these to a 442 guy for $350 this summer. Leave that "O" for the Oldsmobile restoration guy's, besides you'll likely kill it with a high hp build and some stickies For $750 you can put together a decent 8.5.
Well I can tell you they use to race them hard in the day and they did hold from the guys I talked too. You also get bolt in axles. IF the rear is in good shape and ready to roll 750.00 is a very good price as I just sold a posi unit for the 12 bolt olds for 500.00 last week. The posi can use the same internals as the 8.5 10 bolt clutches and spider gears...so if the posi does go it is not IMPOSSIBLE to get parts. Ring and pinions only come in 3.42 3.90 and they only fit the 3 series carrier 12 bolt 'O' type rears have 3 carrier breaks 2.56 - 2.78 3.08-3.23 3.42- 5.86 We are building aftermarket carriers from the 8.8 ford carriers we modifiy the ring gear land and the actual bolt pattern to fit. 28 and 31 spline versions and will fit the aftermarket 3 series gears. I Also sold a complete o type for 1800.00 that was an original T3 code rear for a 442 they are a wanted item to the right guys. Also the rear was used from 1967-1970 there were HD versions in the 67-68 years w-30 High Horse cars this came with 3.42 and up gears and 31 spline HD posi unit. Jim J D Race
I have one of these rearends it is posi with 2.78 gears. Picked it up for $100.00 but was dissapointed to find I couldnt get gears for it. Guess I should find an olds guy to take it off my hands.:grin:
we can get you a spacer to used the Richmond 3.42 or 3.90 gears and you will be good. If you are street bound and some track on special buick weekends etc. with slicks you will be totally fine. I have a 12 bolt chevy rear 2 series spacer to a 3 series and 3.31 gears tester mobile and we have run it all over the street and at the track 12.90 with slicks for 12 years now ...NO issues and that was USED 3.31 back then...lol. Jim:3gears:
Larry... do you really have over 12,000 posts!!!! Holey MOLEY!!!:laugh: You need to get a hobby...Like maybe cars or something....
