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-   -   Please help ID my GM 12 bolt (http://www.hotrodders.com/forum/please-help-id-my-gm-12-bolt-210213.html)

akorcovelos 12-12-2011 06:42 PM

Please help ID my GM 12 bolt
 
Been searching around the net, mostly here, and can't find much to help me ID this rear end. It came out of my '72 Chevelle, but I have no idea if its original.

The numbers I can find are all on the pumpkin, nothing on the tubes. I found the following (pics below):

GM53
3969278N
12345
67890
H299
00N1 or I

The housing is 55" or 54 1/4" long from dust shield to dust shield.

The cover is 10.5" wide.

http://i224.photobucket.com/albums/d...x/IMG_0215.jpg
http://i224.photobucket.com/albums/d...x/IMG_0214.jpg
http://i224.photobucket.com/albums/d...x/IMG_0213.jpg
http://i224.photobucket.com/albums/d...x/IMG_0212.jpg
http://i224.photobucket.com/albums/d...x/IMG_0211.jpg
http://i224.photobucket.com/albums/d...x/IMG_0210.jpg
http://i224.photobucket.com/albums/d...x/IMG_0208.jpg
http://i224.photobucket.com/albums/d...x/IMG_0209.jpg
http://i224.photobucket.com/albums/d...x/IMG_0207.jpg
http://i224.photobucket.com/albums/d...x/IMG_0206.jpg
http://i224.photobucket.com/albums/d...x/IMG_0202.jpg
http://i224.photobucket.com/albums/d...x/IMG_0201.jpg
http://i224.photobucket.com/albums/d...x/IMG_0199.jpg

The car was wrecked and I'm in the process of fixing it. The drivers axle was bent at the flange and I need to replace it. I'm taking it to Dick Strang in Waukegan, IL for a refurbish, new axle, control arm bushings, wheel bearings, c-clip eliminators, and a disc brake conversion, so I would like to go there knowing what I have and what I need to source for parts.

Thanks, this site has been a tremendous help since I got this car! :thumbup:

cobalt327 12-12-2011 07:16 PM

A quick search shows 3969278N to be a '70-'72 Chevelle 12 bolt. The date code H299 is August 29 of '69, so this would have likely been used in a '70.

There should also be some stamped (not cast like on the center section) numbers on the axle tube.

akorcovelos 12-12-2011 07:33 PM

Thanks Cobalt! I'll go have another look on the tubes after I scarf some dinner down, BRB! :)

akorcovelos 12-12-2011 08:23 PM

ok, I found some stamped numbers on the pass side tube front side. Best I can tell it reads: C6H 0909B

I'll let the pics do the talking, maybe I'm reading it wrong.

http://i224.photobucket.com/albums/d...x/IMG_0219.jpg
http://i224.photobucket.com/albums/d...x/IMG_0218.jpg
http://i224.photobucket.com/albums/d...x/IMG_0216.jpg

If there is anything under that cover that will answer some questions let me know what to look for and I'll go pull it off and take a couple pics.

Thanks for the help!

cobalt327 12-12-2011 11:09 PM

You were close- it's actually "CCH". Means it was originally a 2.73:1 posi. The "0909" is September 9, which corresponds to the August 29 casting date.

The "B" is Buffalo, NY assembly plant.

akorcovelos 12-13-2011 08:05 AM

Ok, so originally it had a 2 series carrier? If I pull the cover can I id the gear set and carrier that's in there now? What should I look for when snapping pics?

SSedan64 12-13-2011 08:35 AM

The Ring Gear will have the Pinion & Ring gear teeth numbers stamped, Part #'s & Date.
Example 41-11 = 3.73, 41-10 = 4.10, 41-15 = 2.73

Carrier will have:
Casting #-----Series----------Gears-------
ED32088------- 2--------- 2.73:1 & down
30140PM1------ 3-------- 3.08:1 to 3.73:1
EDB30174------ 4--------- 3.90:1 & up

akorcovelos 12-13-2011 08:40 AM

Great info, thanks! I'll pull it apart tonight after work and update the thread.

akorcovelos 12-13-2011 05:51 PM

ok, pulled the diff cover and I'm a little confused.

it looks like the number on the carrier is ED -32088 which would be a 2 series, but the number on the ring gear is 2 GM 3862525 11 41 3 67 which is a 3.73:1?

http://i224.photobucket.com/albums/d...x/IMG_0228.jpg
http://i224.photobucket.com/albums/d...x/IMG_0221.jpg

SSedan64 12-13-2011 06:08 PM

Someone used a Ring Gear spacer which allows you to use 3-Series Gears in a 2-Series Carrier. :mwink: Not the strongest method but, they work.
Looks like March, 1967 GM gears.

cobalt327 12-13-2011 06:13 PM

And you're correct on them being 3.73's.

akorcovelos 12-13-2011 06:19 PM

hmm, how much power is this setup good to?


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