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Identify differential?

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Old May 17, 2007 | 08:33 AM
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Default Identify differential?

Can anybody help me identify my rear axle/differential? I have been looking on the internet but have not been able to find anything.

I found the following data on it:

2 AZ 11 8 67W

Last edited by Ronaldo; May 17, 2007 at 08:37 AM.
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Old May 17, 2007 | 09:08 AM
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AZ is a 3:55 ratio for a BB. The date is probably Jan 18 67.
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Old May 17, 2007 | 11:04 AM
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Originally Posted by Ronaldo
Can anybody help me identify my rear axle/differential? I have been looking on the internet but have not been able to find anything.
I found the following data on it:
2 AZ 11 8 67W
2=2nd shift
AZ=3.55 heavy duty(big block) positraction

11 8 67 - sure there isn't another number there?
Month was a 2 digit number, so January would be '01' etc
Day had a 2 digit also ... sometimes.

January 18, 1967 ?? ... for a 1967 Corvette
November 8, 1967 ?? ... for a 1968 Corvette
(Both '67 and '68 Corvette used the same AZ 3.55HD code)
I suspect, if they're spaced as you indicated, it is the Nov 8 date.

W=Warren Michigan assembly plant
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Old May 17, 2007 | 11:30 AM
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thanks for the quick answers both of you

hmm my car was assembled in november '67, can this differential be the car's original?

I have a not original 327 cui with a fake big block restamp number on it, in my car now.

Are there other ways to check if my car was originally a big block?

Last edited by Ronaldo; May 17, 2007 at 12:17 PM.
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Old May 17, 2007 | 03:06 PM
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If the car was built Nov. 67 then it is a 68. AZ code was not used in 68 so, I would say it aint the one that came there. You never said that it was a 68.
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Old May 17, 2007 | 03:34 PM
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Originally Posted by Ronaldo
thanks for the quick answers both of you ... hmm my car was assembled in november '67, can this differential be the car's original? I have a not original 327 cui with a fake big block restamp number on it, in my car now.
Are there other ways to check if my car was originally a big block?
Yes, there's a very good chance it is original to the car ...
The date coincides with a later November build (my original rear has a date 2 weeks before the car build date)
The AZ code (3.55 heavy duty big block positraction) was used for 1965-66-67-68 & 69.

To check if the car was a big block .... ???
what is the tach red line?
is there a rear sway bar??
out of curiosity, what is the fake restamp number??
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Old May 17, 2007 | 03:41 PM
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It looks like a rear sway bar has been mounted, but removed again. I can't remember what the redline is. There is no return gas pipe either...

Here is the restamp on the picture below

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Old May 17, 2007 | 04:34 PM
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Originally Posted by Ronaldo
It looks like a rear sway bar has been mounted, but removed again. I can't remember what the redline is. There is no return gas pipe either...
The stamp pad sure is a mess ...

In 1968, the big block tach readings were:
427/390 and 427/400hp = 5600rpm
427/435 and 427/430hp = 6500rpm

no return fuel line would indicate a Holley carb, which was the 400, 435 and 400hp versions (427/390 used a Quadrajet).

looks like you have some investigating to do .... good luck.
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Old May 17, 2007 | 05:06 PM
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Originally Posted by FrankVincent
The stamp pad sure is a mess ...

In 1968, the big block tach readings were:
427/390 and 427/400hp = 5600rpm
427/435 and 427/430hp = 6500rpm

no return fuel line would indicate a Holley carb, which was the 400, 435 and 400hp versions (427/390 used a Quadrajet).

looks like you have some investigating to do .... good luck.
thanks
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Old May 17, 2007 | 07:12 PM
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Originally Posted by FrankVincent
Yes, there's a very good chance it is original to the car ...
The date coincides with a later November build (my original rear has a date 2 weeks before the car build date)
The AZ code (3.55 heavy duty big block positraction) was used for 1965-66-67-68 & 69.

To check if the car was a big block .... ???
what is the tach red line?
is there a rear sway bar??
out of curiosity, what is the fake restamp number??
That` ill teach me to rely on the books. The GM parts book did not list the AZ in 68, but upon further review, it does show back up in 69. So, I guess it might just be in 68 also.
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