ID information on my 1970 transmission

[Joe W.]

Hello,

I'm still learning so please be patient.
I'm trying to identify the numbers stamped on my transmission.
1970 Corvette 350/350 4-speed convertible. Please refer to the following:

Drivers' side - Rear: 3952648
There is what appears to be (2) clocks stamped in the casting.
The first reads 3:45 and the second, 10:20.

There is also a metal tag with numbers/letter stamped on it.
7M110896.

Passenger side - Rear: 392561
Then, U.S. Patent # 308833 with the last number as an 8 or 6.

Thank you.

Joe

[Joe L.]

Re: ID information on my 1970 transmission

Hello,

I'm still learning so please be patient.
I'm trying to identify the numbers stamped on my transmission.
1970 Corvette 350/350 4-speed convertible. Please refer to the following:

Drivers' side - Rear: 3952648
There is what appears to be (2) clocks stamped in the casting.
The first reads 3:45 and the second, 10:20.

There is also a metal tag with numbers/letter stamped on it.
7M110896.

Passenger side - Rear: 392561
Then, U.S. Patent # 308833 with the last number as an 8 or 6.

Thank you.

Joe

Joe----


The GM #3952648 is the side cover used for Muncie transmissions from 1970 to 1974. So, it's the correct one for your trans and year. The "clocks" really have no importance on these die castings.

I think the number you have as "392561" is actually 3925661. This is the casting number for the Muncie main case used from 1970-74 for all Muncie variants.

The metal tag is somewhat of a mystery. Generally, these tags will have the GM part number of the transmission embossed on them. However, "7M110896" is not a GM part number, so I don't know what that is.

[Joe W.]

Re: ID information on my 1970 transmission

Joe,

Thank you for the info.

Joe

[Mike E.]

Re: ID information on my 1970 transmission

Joe--
Have you taken the metal tag off the tranny?
My guess is that you read it upside down, and that the "3" is very close to the bolt, and what you actually have is 3968011ML
The 1970 AIM sheet M20 A4 item 7 lists 3968011 as the M21 with L46 and LS7.
What the ML means I have no idea.

[John H.]

Re: ID information on my 1970 transmission

What the ML means I have no idea.

Mike -

The "ML" is the broadcast code for that transmission.

[Joe W.]

Re: ID information on my 1970 transmission

Joe--
Have you taken the metal tag off the tranny?
My guess is that you read it upside down, and that the "3" is very close to the bolt, and what you actually have is 3968011ML
The 1970 AIM sheet M20 A4 item 7 lists 3968011 as the M21 with L46 and LS7.
What the ML means I have no idea.

Mike,

Thank you for the info.
I have not removed the tag.
It was on the car when I bought it.
It proves the transmission is original to the car.
L46 350/350.
Joe

[Joe L.]

Re: ID information on my 1970 transmission

Mike,

Thank you for the info.
I have not removed the tag.
It was on the car when I bought it.
It proves the transmission is original to the car.
L46 350/350.
Joe

Joe-----


If the number on the tag is what you originally reported, I don't know what that proves (or, disproves). If it's actually the number that Mike mentioned, then that would indicate that the transmission COULD BE original to the car.

More-or-less "proof-positive" of whether the transmission is original to the car is indicated by the VIN derivative stamping which is found on the rear vertical surface of the main case. If the VIN derivative matches the last digits of your car's VIN number, then the transmission is original to the car. If it doesn't or there aren't any numbers, then it's not original to the car. Simple as that.