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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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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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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. :confused:

{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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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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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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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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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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Most judges I know aren't gonna go looking for the casting date or the stamp on the axle tube!!
 

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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.
 

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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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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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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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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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Where does he say it's going to be judged? The answer to his question is, It's not the correct rear axle for the car. JMHO!
 

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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?
Hey Robert, sorry to drag this post out of mothballs, but I ran across it while doing a search because I was facing the same questions. I have a third week of February, Arlington-built '70 SS454, but mine is an LS-5. Like yours, my rear axle code is "CCF" but with 4.10:1 gears. For the 17 years I've owned the car, I always just thought that the CCF was probably an "Arlington accident" as they were known for, and that, at some point, somebody replaced the 3.31:1 gears usually associated with CCF axles, with 4.10 gears. Now it appears that mine might be like yours, and the mystery solved. I reached out to Dale M. who runs the LS6 Registry, to see if he ever made any progress in researching the cars with POPs known to have been built like this in Arlington. Did you ever make any headway in your research?

- Nate
 
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