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Discussion Starter #1 (Edited)
I own a 1970 Nova released the 5th week of September 1969. It's a number matching CNJ block 300 HP 4 speed.
There are missing parts, namely the M21 transmission and the build sheet. What is stumping me is the rear end also coded 09/30(1969).

It is code CBM, which would indicate a 3:31 open axle. However it bears the cast#: 3969341NF and contains a positraction ring and pinion coded 9/41.
All the web disinformation indicates the rear: Code CBM 09 30, is a 3.31 open differential.
But the housing is cast: 3969341-NF, which according to NovaResource - Nova Rear Axle Codes (and Chevy by the Numbers, Alan Colvin) indicates this axle housing was only used in applications above 3.90:1.

If the GM crew voted to strike on 09/24/1969, Wednesday, what might have have happened the week after?

The build date of my 1970 Nova SS / 4 speed is 09E, per the cowl tag. The rear end date code is: 09/30/1969, ie: week 5, or by Tuesday. The block is similar (at the machine shop)

What really happened?
Why would my car be "unidentifiable" (on the internet) when I have the original engine block and rear end?

I've shown the original block with original number matching VIN code. If you have my matching transmission case, a Muncie M21 code P09P, contact me.
 

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First, I know nothing about the UAW strike in 1969, but the 09E is the Fisher build date of your car's body, not the production date of the finished car. Generally, the difference in the body build and production dates is just a few days. During periods of labor unrest and strikes, this can become many weeks . You would need to know the actual date the finished car rolled off the Chevrolet production line to really understand what might have happened. There was no requirement for build sheets to be placed in cars, so without other original factory documentation it may remain a mystery.

Bob
 

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Discussion Starter #4
Chevy is known to have released some odd combinations, or the PO may simply have changed the gears. My point is the ring and pinion (4.56:1) appear original and are dated appropriately. I've never seen a comment on the meaning of "X" on an axle. I have seen a comment indicating G-2 means Detroit, 2nd shift. Not sure about that interpretation. 2 - X may never be explained. January is a late build date. September is early.
 

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January is mid year, but maybe the original owner of your Nova had those 4.56 gears installed at the dealer at some point?? You should send in $50.00 to NCRS for a shipping data report on your Nova. It will tell you the official production date of your car and dealer it was shipped to. This might help with the date of your differential.
 

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Discussion Starter #6
Thank you, Mr. Nickey. Wasn't aware of the possibility and will look into it. But, really? A Corvette society?
 

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yes on the NCRS for info. i sent the 50.00 bucks got the date my nova was made an the dealer it was shipped to. the document came to me on their letter head with a gold stamp at the bottom with the corvette logo on the stamp. i'd say it took 3 weeks to receive the info back. so what i found from them is my 66 was shipped to rapid city, SD. an is now in michigan. i called the dealer listed from the corvette document an they had nothing on a 54 years old sale. oh well a dead end. then i sent to DMV in SD an they had nothing on their info for my nova. dead end.
 

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Discussion Starter #8
Appreciate the affirmation, Redrider66SS.
We would all like to know everything about our Nova, from the day it was conceived to the day it became "mine," no matter how esoteric.
Case in point tonight removing lower ball joints: one looks very original, the other not so much. One presses out like butter. The other not so much.
Hmmm... then there's that dent/scratch on the underside of the sub-frame (which has been previously repainted):
Who wrecked my car and when?! We want to know, right?
$50 to know what dealer sold it originally and what date it left the factory?
For $10 I'd do it yesterday. But there's a definite line between supply and demand and $50 might cross it.
Still, I want to know and this is an Originality thread.
Hmmm... For today I have ball joints to install though my eidetic memory will haunt me now that I've finally seen it spelled correctly.
Or is that just me being tenacious again.
 

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Discussion Starter #9
Oh, I didn't miss Mr Nickey's comment...
"I have the same 341-NF casting rear you have, but coded CBS 3.31 posi. in my 70 L34 Nova. My car is a January built Nova."
This means the disinformation saying this diff was only used on installs above 3:90 is questionable.
 

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There wasn't many gear ratios to choose from in 1970 compared too 1969. For 1970, 3.31 was a standard gear with 3.55 as a option and was standard with the L78 option. If you wanted a lower gear, like 4.56 or 4.88 you could install it yourself or have the dealer install. That's what I'm thinking happen with you Nova.
 

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There wasn't many gear ratios to choose from in 1970 compared too 1969. For 1970, 3.31 was a standard gear with 3.55 as a option and was standard with the L78 option. If you wanted a lower gear, like 4.56 or 4.88 you could install it yourself or have the dealer install. That's what I'm thinking happen with you Nova.
Yes, not much in the way of gear ratio choice in 1970. 3.55 for the L78 was pretty tame. Even back in 1966, you could get 3.73 for your 350HP Chevy II. Some L78s had the gears changed before they were even delivered. My '70 had 4.10. Not for everybody, especially those who are interested in gas mileage or extended periods of highway driving.

Bob
 

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Discussion Starter #12
I'm going to drive by the P.O.s house on the way home. I wonder what he'll say...
 

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Discussion Starter #13
So... I visited the PO tonight. He remembers 3:08 open. The Code says 3:31. He did change the ring/pinion w/ factory parts w/ the goal of the local drag strip and a turbo-hydro..
Now, I know. Codes are truth.
The trans... allegedly now in a 60's Impala. Still hunting.
 
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