GM 12 Bolt Date code

[bearcat]

I am trying to figure out what the heck this rear end came from. Where the date code is GM52 and the stamp is 3894860NF (best I can tell) Anyone know what it is? I have scoured the internet.

Thanks,

[vintageracer]

Have you checked the Oldsmobile codes? BOP (Buick, Oldsmobile, Pontiac) also had 12 bolt rearends. They are are not as strong or desireable. Easily identified by the rear cover with still has 12 bolts but is different in design from the Chevy rearend.

Chevy rearends will have a casting date on the rearend at the bottom of the rear center section in a recessed area. Look next to the rear end cover bolts at 5 and 7 o'clock.

Do an internet search and look for a site that shows the rear cover of a BOP 12 bolt and a Chevy 12 bolt for quick/easy identification.

Typically the BOP 12 bolt will have a round bubble cover where the Chevy will have a large rib pressed into the cover.

[bearcat]

Thanks, did a search from the casting number. I spent most of my time researching the date code. Looks like a 67-69 camaro 12 bolt.

Still cannot find an answer on the date code though. I need to scrape more muck off it.

[chicane67]

3894860 67-69 12 bolt

http://www.camaros.org/drivetrain.shtml#RearAxleNumbers

As for the rest... you'll see from the link that you will need a few more numbers off of the housing to get the answers you are looking for.

[ProdigyCustoms]

Neither of those numbers are the date code.

The casting date (the date the center section was cast, not the day the rear end was assembled) is in one of the (4) triangle webs in the around the rear cover and will be letter, (2) digit number - single digit number. Something like A 12 7 which would be January 12th, 67. Or E 18 9 which would be May 18th 1969

On the front of the passenger side axle tube, half way between the center section and axle tube end, on the front of the tube, will be stamped letter with something like BU0524 E which would be BU=3.73 Posi, 0524 would be the assembly date of the rear which in this case is May 24th, and the E for Eaton Posi. And you refer back to the casting date for the year.

Also, if it is a 67 Camaro 12 bolt, it will be a one year only mono leaf perch and have a traction bar bracket on the right axle tube, also one year only.

[chicane67]

Not necessarily... Frank. My early 67, L30/M20 12 bolt had no traction bar and/or bracket. This surprisingly was verified by my 'protect-o plate' and two cats over on Camaros.net that are some part of CRG. Although for this to be true... I believe it would have to be date coded around/before mid month October, 1966.

Albeit very rare... the early L30/M20 California 67's (not yet defined as NOR or LOS specifically) in this case also had no front subframe tie-down holes. Dave Pozzi and I, thus far... are the only ones that actually have one of these subframes or have seen/doccumented one to any extent.

But yes... if it were a 67 specific housing... it would be a mono leaf. That is for sure.