1970 Muncie M-22 trans code ID help

[al8apex]

This trans came out of an early 1970 Chevelle SS396 L78 that I bought at the Pomona swap meet in the mid 80's.

The person I sold it to converted it from bench 4 speed to bucket auto, changed the colors and it was a feature car in Super Chevy way back then. I bought the trans from him as an extra for my 70 M22 Z28 (knowing way back then that it was a one year trans, JUST IN CASE anything happened to mine).

FFWD to today and his brother inherited the car and wants to change it back to the 4 speed and wants the "original" transmission for the car.

IIRC a thread I was looking at (and can't find today) had VERY similar numbers stamped into it and some suggested it was a replacement trans.

Here are the pictures I have and your input is appreciated on if that theory is fact or ???

Thank you for your opinions / facts / insights, etc

[Ls6 Ragtop]

Jim,
Your transmission is indeed an over the counter transmission. CTO is the code used for complete transmission assembly for 1970 (the 0 after the CT is the year) and CC0 was used for replacement case i.d. in 1970. Your trans has the CT code and an assembly date proving it was sold as an assembled unit.
BTW I don't know of any documented Chevelle L78 cars with the M22 trans. M22 for the 396 motor was coded 3968012WM as was the Corvette and Camaro versions I've seen in 70. 454 Chevelles used the 3978766WO coded M22 in 70-71.
Hope this helps, Chris

[Mr70]

Everything Chris mentioned is right,plus the fact that the 1970 L-78 equipped Chevelle was not eligible to receive an M-22 transmission on the assembly line from any one of the 5 vehicle assembly plants @ that that time...only an M-20 or M-21 was possible,when ordering from the M/T family.
Your over the counter M-22 looks like it shows it was the 42862nd unit assembled on August 29th,1970 out of the 1000 over the counter service units available from their Muncie plant that year.
You also show it has the #7584 extension housing,which I believe means it was intended to be installed as a service replacement in a Corvette or Camaro..not Chevelle,which used the #8764 housing.
I'm curious to know if your M-22 has fine spline input/output shafts & if it has a drain plug?..as it might have been assembled in August 1971.

[YENKO DEUCE REGISTRY]

If it was assembled in '71 would it not use a 661 case, or could it have still utilized a 660 unit?

[al8apex]

this is a 69 assembly for the 70 model year. It is NOT a 71 style trans with the fine spline input shaft. It DOES have the drain plug.

The car I bought was a gold 1970 Chevelle SS 396 L78 with the original engine and a black vinyl roof, matching black vinyl interior. It had a 4 speed and he said it was an M22, I never cared to look at the numbers way back then, only the engine number. It DID NOT have a fresh air hood. He bought it on the cheap (not sure why he popped for the vinyl roof though) and it only had performance options as I recall, hence the bench seat. I can't remember if it had ps or not, it DID have posi. I do not believe that it had stripes either, but I am not sure on that point. I DO KNOW the paint was chalked out and the car was fairly ugly with the chalky gold and the black vinyl roof, but it was wicked fast.

2 high school buddies were selling their cars at a mid 80's Pomona show that they had bought new in high school and I bought them both.

I do not remember IF the POP was with the car or not, his name was Leonard, that is all I can remember. His buddy had a black 69 Mach 1 that he had put an earlier SB Ford in so as to evade the SMOG rules in CA at the time. I think it was a 64 engine with a trans to match.

Here is a summary of info on the trans from the other sites:

CT = Complete Transmission
0 = 1970, CT0

P0M29, as stated above:
P=Muncie
0=1970 MODEL YEAR
M=August
29=day of month
C=M22

From sYc:

CTO is the code used for complete transmission assembly for 1970 (the 0 after the CT is the year) and CC0 was used for replacement case i.d. in 1970. Your trans has the CT code and an assembly date proving it was sold as an assembled unit.

From Team Chevelle:

This appears to be a service replacement transmission because it is stamped CT042862. This is the same manner in which service replacement engines were identified with CE numbers except that transmissions used a T instead of E. The 0 after CT indicates the 1970 model year followed by the sequence number 42862. That is all I can recall, I know I have a Chevrolet bulletin about this somewhere, but haven't found it yet.

The 660 cases were used early in the 1970 model year, also, so this is a relatively early replacement transmission for 1970, This one being assembled in August of 1969.

So it is not the original for the car, but it is probably the best replacement to go back in the car.

&

The 660 main case is supposedly a 69 item, so I guess it's conceivable that a very early production 70 received that. And of course the P0M29C stamping is consistent with the trans being intended for very early 1970 production.

It's generally accepted that 'CE' stamping on an engine indicates a 'C'rate/'C'ounter/'C'hevrolet 'E'ngine, so it's also consistent that 'CT' stamping would be for a transmission. And the remainder of the stamping is NOT consistent with any CON VIN, so it certainly ***could*** indicate that this was a replacement transmission that was installed in an early production 70 model car very early in its life.

So....in reference to your question.....if the brother now wants the "original" transmission for the car, what you have may be as close as he can ever get to that request.

&

Yes, that is a replacement trans. I think it breaks down as C=Chevrolet, T=Transmission complete (a "C" here would be just a replaced case), and 0=1970. The 42862 has something to do with the sequence number of the trans, not a number that would match the Chevelle it came out of.

[Fast67VelleN2O]

FYI... I have owned a few 660 cased 1970 Muncies. They are all very early units. August and early September only.

[YENKO DEUCE REGISTRY]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fast67VelleN2O</div><div class="ubbcode-body">FYI... I have owned a few 660 cased 1970 Muncies. They are all very early units. August and early September only. </div></div>

Learn something every day, thanks.