www.jdrace.com

I bought this differential for my 1967 Cutlass Supreme Convertible. The 5.00 gears are too steep for me, even with a 200-4R. From the research i’ve done the 672 carrier has a range of 3.42 to 5.00 and has 31 splines. After disassembly I noticed that the axles are 28 spline. Is this an oddity that Oldsmobile made?

Here are some part numbers I have found.
#672 carrier posi with 5.00 gears.
All bearings are oiled and not sealed type.
Carrier bearings: Timken LM603013
Axle bearings: Timken U261L
Axle length: 29 3/4”
Axle spline: 28
Axle seal inside: 13492
Ring gear: 45A9 GM SL 238 2 (10 bolt)
Pinion: 4053 10 245 scribed 328B
Housing #: 402227 CFD 6 date code 343 (12 bolt cover)
Housing length: 55 1/2”

Thanks for any advice.

More pictures to previous post. I can only assume it is a 402227 housing.

oK, wELL welcome to the site...Hope we can straighten some stuff out for you.
The deal :
672 casting is 31 spline only... Some one has obviously been inside the carrier and swapped out the side gears IF a 28 spline axle fits this carrier.
672 carrier holds FACTORY ratios as follows 3.42 3.90 4.33 4.66 5.00

You want to lower your differential ratio down to a more reasonable driving range with a 200r4 trans.
3.42 or 3..90 could work nice.
trouble with the 672 and the 588 carrier is they can only hold FACTORY gears... 3.42 - 5.00

All aftermarket gears fit the 3 series carrier 671
Aftermarket ratios are 3.42 and 3.90 they DID have 4.10 about 10-20 years ago but we have not seen them in a long time.
We have aftermarket gears 3.42 and 3.90 on the shelf
We have Aftermarket NEW yukon 3 series posi unit that use the 3 series aftermarket gears AND 3.08 and 3.23 factory gears.
We have aftermarket bearing kits and axle shafts also

What you need to figure out is how much you want to spend on getting this correct and what ratio you are looking to be in for your combination.

do the axles (28 spline ) fit the 672 carrier side gear? If so then we know that unit is not correct. should be 31 spline. Worries me that the unit is even set-up correctly or just thrown together??
Jim
JD Race

Jim thanks for responding.
So this is not a super secret Oldsmobile experimental racing only 5.00 ratio 1of1 442 W30,W-27 posi? Darn!
I do like the uniqueness of the set up. I’m building the car to be for street cruising and an occasional jaunt to the track. With the differential apart now I just want to know what options I have. One of the spider gears has marks on the face of several teeth. Maybe a carrier rebuild is in order.

Ok here’s another question. Are these the correct axle bearings and seals? When bolted in they were not flush with the flange and there was no gasket. The flange plates are raised between the bolt holes because of being tightened down and not being flush.

More pictures. Bearing race.

wELL THERE IS SOME messed UP STUFF GOING ON WITH THAT REAR END...LOL.
tHEY HAVE EARLY AND LATE MODEL AXLE BEARINGS AND SEALS mixed UP WITH THIS REAR. crazy STUFF.
i REALLY CAN NOT TELL FROM THE PICTURES YOU ARE SHOWING ME.

So, if you have a 1970 12 bolt olds the axles will be 28 spline and have OILED axle bearings and the SEALS will be on the axle shaft.
IF you have 1967 - 1969 the 12 bolt olds will have SEALED bearing set up with the seals in the housing tube end. YOURS has BOTH seals ...this CAN NOT BE!
the axle bearing you have on the axle shaft is a oiled bearing and requires oil from the center section of the rear end and the seal they have installed is BLOCKING the oil from the center to the axle bearing.
WE really need to know what housing you have 67 68 69 or 1970?
Jim

The spider gears on the posi unit look like they are DONE.
So I can see why you were looking for some.
That will be a HARD find as these rears were only used in 67- 70 era...then less were posi and EVEN WAY less 67 68 year only and 3.42 - 500 ratio only were 31 spline units. sooo very needle in the haystack

Jim thanks for all your time and information. It is greatly appreciated.

Does PowerTrax make a unit that fits in the carrier?

Yes and no. We modify a unit to fit into a open carrier. Jim
28 spline only

IT WILL NOT FIT your 672 or any POSI unit carrier case. THEY are totally different. You need a OPEN carrier with just regular open spider gear case.

Just pulled the inner seals from the axle flanges.
Seeing that two different sets of axles seals were installed can either set of bearings (sealed or open roller) be used?
There is no code on the inner passenger side tube, driver side also checked, to tell what year or gear ratio.

No Each bearing has a different OD dimension.
sealed bearing has a OD of : 2.7475
Oiled Bearing has a OD of: 2.5591

CAN NOT be interchanged and even the axle shafts are different. The offset of where the bearing land is machined on the axle shaft.

Latest on crazy 12-bolt. Mock assembled differential after extracting inner seals. Now axels move in and out of carrier about 1/2” on both sides. Any suggestions? Thanks

Temporarily put carrier in. I’m wondering if axle bearings have to be changed out for the sealed kind.