Help identifying a 12 bolt diff
 

Can someone help me identify this differential? I've never tried or had a need to decode a rearend before, but I'm sure someone here has. I would appreciate the help, and if I need to find more numbers off of it, just tell me where to look. THANKS!!!

This article is decent, short and sweet.

https://www.chevydiy.com/history-and...differentials/

Probably a 1968 Chevelle 3.73 gear/posi rearend.


:)

'68 "Chevelle" 12 bolts used the "124" casting center housings.
"038" casting 12bolt "chevelle" housing was used in '69 models. Malibus, Elco's, Chevelles, as well as '69 cast McKinnion c-clip axle A-body 12 bolt rears used in a few '69 Olds & Buick A-bodys. A very few late '69 production "038" casting 12 bolt rears ended up in very early '70 models, from what Ive pulled those were typically 2.73 single tracks.

Original axle tube stamping

CI 06 10 B

CI = 3.73 posi traction
06 = 6 month, June of '69
10 = 10th day
B = Buffalo diff plant

The article is also full of errors.

Thanks for the info guys. I can tell you it is a 3.73 posi. Wasn't sure it was original to the housing but I guess it is. So from the info above it looks like an late 69/ early 70 Chevelle. Thanks again.

http://forums.maxperformanceinc.com/...9&d=1553551641


F 2 8 = June 8th 1968
The CI 06 10 B is correct on being June 10th 2 days after being cast.
No year designation in the stamping.
That '8' could be a '9' but looks like eight to me?


:confused:

I thought it was an 8 at first also. But that casting number keeps coming back as only used in 69.

Anyone want to give me your thoughts on what it's worth? It's complete with backing plates, minus the pinion yoke and nut. It's dirty outside, but internals look good.

It could have been installed in 1968.... as in the last cars for "68" just before the change over to the new 1969 models. GM would run out of "68" parts and use what they had on hand.... new "69" parts so they could fill the last orders for "68" at that plant. And they'd still say 69 only. ;)

Ford did the same thing too.

I had a 12 bolt, same ratio, posi for a 69 Camaro I sold at the Springfield, OH swap meet last year. It was totally disassembled, in a box but 100% complete. Housing was a little rusty, but not bad. The second the swap meet opened and before I had it completely out of the trailer, I sold it for $450.00. Could have easily sold for $600.00. But I wanted it gone, which is why I took it there. The guy who bought it acted like he won the lottery. That may be some gauge for you.

Wouldn't be the first time GM did that. My 3rd week of July '66 GTO has a '67 LH inner fender (for the larger '67 booster), 2 sets of bolt holes in the side frame rails (for the T-400), and I forgot what else...

Mike, from the asking prices I've been seeing, that was a steal for him.

Well, we were both happy that day. When I take stuff to a swap meet, it's to sell the stuff. Not to show it off and drag it home again. I hope it worked out for him.

About 1.5 years ago, I sold my 3.42 posi 12 bolt from a 70 Chevelle. It had Moser axels and disc brakes. I put it on Craigslist, $1300.00. Next day a guy drove 150 miles each way, did not haggle handed me 1300 and left.

I have been running that sale through my mind from last year. I said it was 100% complete, and that was not correct. The assembly did not have ANY axle shafts, backing plates or brake parts. So it was housing, rear cover, center section, case/posi, all gears, bearings, caps, rear cover. So still a deal at $450.00. But $1300.00 for a complete Chevelle unit with disc brake set-up, Mosier axle shafts, and the desirable 3.42 ratio is also a good deal. I can understand why that guy was also excited.

Me too. :confused:
How does the 2 translate into the 8th? Not debating it, just trying to understand.



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Should be Jun 2 1968


8 days before the housing stampings.

Had '8' on the brain I think.

:eek:

The pertinent point is the 8 at the end which is for the year.

:)

Casting is F 2 9, June 2nd, 1969.
Without the yoke you can ask $1000 (although it may probably sell for less, around $800(Craigslist)). Around here anyways.

Is that June 2nd or 2nd week of June?

The casting date is June 2

If the last digit is a '9' it would be 1969.
(just doesn't look like a 9 to me, but hard to tell from pic)

With the casting code for the 69 rear end, it is probably a 1969.
Either way a nice 12 bolt.

:)