Fun71

The axle shafts with sealed bearings from the 67-69 O-Type will not physically fit into the axle tube for a 1970 O-Type that uses the open bearing with seal between the bearing and retainer. Unless someone swapped the axle tubes, that is.

john mann

Hi, i just talked with greg from supercars unlimited yesterday and ordered a pair of 10-16 axle bearings, he told me it was common to find 69 axles in 1970 differentials,
The Oldsmobile 12 bolt rear end (O axle) was used under most 1967-1970 Cutlass, 4-4-2 , Hurst/Olds and Vista Cruisers. The housing cover can be identified from the pictures below. Internally, the Olds 12 bolt O axle rear end features an 8.5" ring gear. Which is attached to the carrier by 10 bolts (this 8.5" 10 bolt ring gear is not the same as the 1971 and newer 10 bolts). All use 28 spline axle shafts except the 1967-1968 models originally equipped with 3.42 thru 5.00 gears. These use 31 spline axles. The 31 spline models also use larger carrier bearings than the 28 spline models. Consequently, the 31 spline carriers cannot be used in a housing originally equipped with 28 spline axles, and vise-versa without the use of special bearings. 1967-1969 axle bearings are a sealed ball bearing design. 1970's axle bearings are an open roller design lubricated by the differential oil. All O axle shafts are retained by a four bolt flange (not internal C-clips). Three different carriers were used depending on ratio: 2.56-2.78, 3.08-3.23 and 3.42 thru 5.00. These have different pinion centerline to ring gear mounting flange offsets (The 28 spline and 31 spline carriers feature the same mounting flange offset). All O axles use a 1.626" diameter, 27 spline pinion stem. All Anti-Spin models (Oldsmospeak for "posi") are clutch type differentials. Which utilize an "S" shaped spring to provide pressure against the clutch packs.

Fun71

I have all three styles of O-Type rears behind the garage, and I don't see how it is physically possible to install the early sealed bearing shafts into the 70 tubes.

I think Super Cars web site even says that:

Please note, over the years we have encountered some very early production 1970 rear ends that utilize the 1967-1969 axle bearings and seals (as well as of course the early style axle shafts and axle tubes).



FYI, the bearings and seals are still available from the local auto parts store:

Axle Bearing: National RW507CR
https://www.oreillyauto.com/detail/b...w507cr/2554210

Oil Seal: National 8594S
https://www.oreillyauto.com/detail/b/national-2929/wheel-bearings-hub-assy-seals-25107/bearings-and-seals-25072/wheel-seal-12871/218fbaa0f6c2/national-seal/8594s/2552428/1972/oldsmobile/cutlass?q=8594S&pos=0

john mann

Greg shipped them out yesterday, i ran out in the garage took my caliper the OD of the bearing is 2.745 and the width is .660 now a mic would be the best way to check this but mine are at work, this is all i have here is my caliper, all i can say is when they get here ill be able to see if they are right or not ! the way he explained it to me was 1967-68 are 31 spline and would not work for me, nor would the 1970 axle with the outside rubber axle seal even though there 28 spline, but if it had the old style bearing and colar on a 1970 axle thats the bearings and colar that i would need, so time will tell, it always does !!
12 Bolt O Axle CARRIER CASTING NUMBERS (O.E. ANTI-SPIN CARRIERS) Casting Number Year Ratio 673 1970 2.56-2.78 28 spline axles 671 1970 3.08-3.23 28 spline axles 588 1967-1970 3.42-5.00 28 spline axles 672 1967-1968 3.42-5.00 31 spline axles

Fun71

Not all of the 67-69 axle shafts were 31 spline - only the Heavy Duty versions got 31 spline shafts; the standard duty ones were 28 spline.
I have a '68 3.23 Anti Spin rear with standard duty 28 spline axle shafts on my car right now. Those shafts are like the ones in your pictures above.
I also have a '68 3.42 rear with Heavy Duty 31 spline axle shafts in storage.
And a '70 2.56 peg leg for, um, parts maybe?

11971four4two

The gear you show in the picture is for a 1969
I know some of the infernal internals are inter change able

john mann

Hi, just got the bearings today, they are 2.748 OD and .656 wide, looks like they will go right in there, john.. i just looked at the website that you put on here for oriellys, man only 21.99 each, i paid double that at supercars 42.95, it was to late for me once i saw your response i had ordered them the day before, i would of put the brakes on and went there and bought them at oriellys! CRAP !!!

Fun71

Well, it's only a $40 difference and you're supporting a company that's good for us Olds folks, so don't lose sleep over it. I used to work at auto parts stores back in high school/college so I'm fairly aware of which parts I can get from the local store and which ones I need to get from a specialty store.