Today I picked up a 12 bolt rear, it had been in a 67 Firebird but the owner thinks it is originally out of a Camaro.
Here are the numbers.
Stamp on passenger side tube-BW12115G1
Casting on front of pumpkin-3894860
Casting tag on rear of pumpkin-K157
any idea what car this rear originally came from?

Do the Firebirds use the same rear ends as the Camaros? If they are different what is the difference?

Firebird used a Pontiac rearend. Quick way to tell is the vent tube is located in the axle tube on the Pontiac. The Chevy rear has the vent tube in the center section. PLus it looks different.

Rick H.

From what I have found so far it looks like it's out of a 68 Camaro.
It has multi leaf perches and 4.56 gears that I think are original, cool.

Thanks for the info gold67, the vent tube is in the center section.

:hurray: after a little more wire brush work I found the letter E under the
BW1215G1 I think the E is for eaton posi.
Sorry for all the posts but I'm very excited to have finally found a 12 bolt :D:hurray:

You must of got a good deal on it

If you want to sell that rearend, I'd like to have it! Kevin

Today I picked up a 12 bolt rear, it had been in a 67 Firebird but the owner thinks it is originally out of a Camaro.
Here are the numbers.
Stamp on passenger side tube-BW12115G1
Casting on front of pumpkin-3894860
Casting tag on rear of pumpkin-K157
any idea what car this rear originally came from?

Most likely came out of a solid lifter Camaro.

Strange, why did GM not use the same parts in different lines? Was it that they really wanted to differentiate the product brands?

alan

Same reason why they don't today - stupidity!

From what I've seen the POB lines used a cone style posi that turned smoother than the Chev clutch posi, but didn't always hold as well. I think it was a matter of comfort, as the other 3 weren't into the HP scene as deep as Chev. You can't rebuild a cone style either.

Here is a pic of the #s
http://img.photobucket.com/albums/v156/mrama/DSC00102.jpg
I plan on using the 12 bolt in my 69,now if I could just find another for my 67.

Strange, why did GM not use the same parts in different lines? Was it that they really wanted to differentiate the product brands?

alan

It was all about "divisional product content"; if Pontiac used their own axles, they'd make more money on the car and maintain volume for their own axle plant; if they used Chevy's axles, they had to pay a markup for them (which made them more expensive than their own axles), and lost volume for their own manufacturing operation. When I represented the GMAD Chief Engineer every month at the corporate Chief Engineers' Meeting, there were "content battles" between the car divisions (and Fisher Body) that would make your eyes water - internal competition between divisions for "content" was fierce. :)

:beers:

It was all about "divisional product content"; if Pontiac used their own axles, they'd make more money on the car and maintain volume for their own axle plant; if they used Chevy's axles, they had to pay a markup for them (which made them more expensive than their own axles), and lost volume for their own manufacturing operation. When I represented the GMAD Chief Engineer every month at the corporate Chief Engineers' Meeting, there were "content battles" between the car divisions (and Fisher Body) that would make your eyes water - internal competition between divisions for "content" was fierce. :)

:beers:

I don't doubt that for a second. Ive built many non-Chevrolet GM cars, and often times have scratched my head wondering why they did some of the things differently (not necessarily better/simpler), only to come to the conclusion that they did it "just to be different".

John, you are a treasure!