70 rear end confusion - Chevelle Tech
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post #1 of 16 (permalink) Old Apr 22nd, 19, 11:03 PM Thread Starter
Bob
 
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70 rear end confusion

I'm finishing up my 70 SS LS6, which I found a little over two years ago in North San Diego County, but I'm more than a bit confused about the rear end casting numbers and dates. To start with, it's an Arlington built car, with a production date of 2/18/70. And, I'm told it could be a bit like the wild west down there when it came to grabbing parts for cars if they were out of stock for what they needed. To start with, the part number on the casing is 3969278NF. But the casting date, located on the right rear of the spider web, is 220. No letter designating the month. It's flat as can be where the letter designating the month should be, like it was never pressed with a letter. But from the looks of it, I'd be shocked if it wasn't the original. Next, I did a review of the Chevelle LS6 registry, and 2 of the 28 cars listed from Arlington are shown with CCF rear ends, both supposedly with 4:10 gears. Mine's a bench car with a 4 speed M22, so it probably should have been stamped with a CRV if it had 4:10 gears, but the gears are definitely 3:31s. And it's stamped CCF 0501B1. So it's a posi rear end, and the gears are definitely 3:31. Wouldn't a 0501B1 axel code mean it was produced May 1st, Buffalo plant, 1st shift? And if that's the case, how could this rear end have sat around on a shelf until February the next year?
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post #2 of 16 (permalink) Old Apr 23rd, 19, 10:01 PM
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Re: 70 rear end confusion

Just a guess on the 220= first 2=February- Second 2= 2nd day- 0=70. I have no clue as to the stampings!!

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post #3 of 16 (permalink) Old Apr 23rd, 19, 10:27 PM
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Re: 70 rear end confusion

According to what we have here; https://www.chevelles.com/years/70/70rearcodes.html
A 70 3.31:1 Positraction 12 bolt stamp code is CCF
May 1st date code doesn't make sense to me though.

{edit} I just noticed it could also be CRV

1970 Rear Numerical Codes (X=Positraction)

Code Positraction Ratio
CCA 3.08
CCD X 3.07
CCE X 3.08
CCF X 3.31
CCH X 2.73
CCN 2.56
CCO X 2.56
CCP 2.73
CCW 3.31
CCX 3.07
CGA 2.56
CGB X 2.56
CGC 2.73
CGD X 2.73
CGG 3.36
CGI X 3.36
CKD 2.73
CKF X 3.55
CKJ 3.55
CKK 4.10
CRJ 2.56
CRK X 2.56
CRU 3.31
CRV X 3.31
CRW 4.10
DKC X 2.73

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Last edited by Dean; May 2nd, 19 at 3:58 PM.
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post #4 of 16 (permalink) Old May 1st, 19, 8:22 PM
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Re: 70 rear end confusion

I ordered my 70-LS-5//M-22 in Feb. 70. ( El Camino) It was built 2nd. Wk. March/ Balt. I did order G-80. My rear is coded CRV.--AKA 3:31 P.
Bob


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post #5 of 16 (permalink) Old May 2nd, 19, 10:12 AM
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Re: 70 rear end confusion

More than likely that would be a replaced rear end. I don't know what the judging gurus consider to be acceptable time gaps between components. However, as someone involved in manufacturing for decades it is possible for several months to pass on parts after they are made and before they are installed. Not "frequent" in the big scheme of things, but possible. And it doesn't mean it was sitting on a shelf necessarily. I have seen rear end assemblies that fail some test or inspection get sent out to subcontract repair facilities. This can take weeks or months before they complete a rework cycle and make it back to the line. Parts can be grabbed off the line and sent to R&D because some engineer wants to do some checking or comparison for a design change or whatever and keep it there for weeks before he returns it. A subcontractor that is building shipping crates for components can ask to have an actual assembly sent to him so he can design his crating or dunnage around it and he keeps it for weeks or months before returning. In short the reasons for extended delays in manufacturing are endless. However, those may not be recognized or acceptable to experts so, like I say, I have no idea if it is considered kosher or not to have that time gap.
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post #6 of 16 (permalink) Old May 2nd, 19, 3:35 PM
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Re: 70 rear end confusion

Did the 331 gear ratio rear end come in a peg leg and posi version?
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post #7 of 16 (permalink) Old May 2nd, 19, 3:59 PM
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Re: 70 rear end confusion

Quote:
Originally Posted by eagleguy View Post
Did the 331 gear ratio rear end come in a peg leg and posi version?
Yes

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post #8 of 16 (permalink) Old May 2nd, 19, 4:04 PM
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Re: 70 rear end confusion

I would like to throw this into the mix! I have a 1970 SS 454/ M-22 El Camino that I ordered in Feb. of 1970. It was built 2nd Wk. March Balt. It is a tlr. Queen and 100% Numbers matching.
Every piece of glass, EXCEPT the windshield is Org. to the Camino. While doing the Resto. I am looking at all the glass, 2 wings, two door glasses and the rear window.
FOUR of the five pieces of glass are ( LOF ) date coded correct for my March build. The right front wing window is date coded mid, 1969 and it is a ( PPG ) vent glass. Like I said, Except the windshield, The FIVE pieces of glass are ORG. to the Camino.
........................ SO, How did this happen?..........................................
Bob


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post #9 of 16 (permalink) Old May 2nd, 19, 4:33 PM
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Re: 70 rear end confusion

Wouldn't a 0501 1969 date still be considered a '69 axle therefor not having the first "C" in the axle code? I guess what I'm saying is since it has the CCF code isn't it likely that it's 0501 of 1970, not '69?
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70 L34 M20 VERT 28-A 791
70 LS5 M40 COUPE 19-19 787
70 LS6 M40 COUPE 14-14 756
70 L?? M?? COUPE 926-99616-755
69 L78 M21 COUPE 71-B 756
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post #10 of 16 (permalink) Old May 2nd, 19, 10:20 PM
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Re: 70 rear end confusion

Most judges I know aren't gonna go looking for the casting date or the stamp on the axle tube!!
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post #11 of 16 (permalink) Old May 3rd, 19, 7:38 AM
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Re: 70 rear end confusion

Quote:
Originally Posted by LeoP View Post
Most judges I know aren't gonna go looking for the casting date or the stamp on the axle tube!!
No, but it helps validate the car unless he has bullet proof documentation.

70 L34 M20 VERT 28-A 791
70 LS5 M40 COUPE 19-19 787
70 LS6 M40 COUPE 14-14 756
70 L?? M?? COUPE 926-99616-755
69 L78 M21 COUPE 71-B 756
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post #12 of 16 (permalink) Old May 3rd, 19, 2:33 PM
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Re: 70 rear end confusion

Quote:
Originally Posted by Dean View Post
Yes
To add to this, there were two different versions of the 3.31 posi (and non-posi) rear as well (as shown with Dean's codes above). The difference is in the pinion flange (396/SBC vs 454).

So four possible codes for a '70 Chevelle 12-bolt with 3.31s.
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post #13 of 16 (permalink) Old May 3rd, 19, 2:46 PM
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Re: 70 rear end confusion

Quote:
Originally Posted by novadude View Post
To add to this, there were two different versions of the 3.31 posi (and non-posi) rear as well (as shown with Dean's codes above). The difference is in the pinion flange (396/SBC vs 454).

So four possible codes for a '70 Chevelle 12-bolt with 3.31s.
Correct. The CRV and CRU 3.31 codes are only on 454 cars as the rear axles have a 1330 pinion yoke vs a smaller 1310 yoke found on all other 12 bolt equipped cars.

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post #14 of 16 (permalink) Old May 3rd, 19, 5:59 PM
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Re: 70 rear end confusion

Quote:
Originally Posted by blacknblue View Post
Wouldn't a 0501 1969 date still be considered a '69 axle therefor not having the first "C" in the axle code? I guess what I'm saying is since it has the CCF code isn't it likely that it's 0501 of 1970, not '69?
That would be my guess also and the casting date to me looks like D 220 (April 22 1970).

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post #15 of 16 (permalink) Old May 3rd, 19, 10:12 PM
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Re: 70 rear end confusion

Quote:
Originally Posted by blacknblue View Post
No, but it helps validate the car unless he has bullet proof documentation.



If one decides to sell saying it is a matching numbers car, then yes, but for judging purposes, It really isn't gonna matter! JMHO!

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