M22 Service (over-the-counter) transmission

[Wayne M.]

This was installed in 1971 or 2 in my '65 396 by the (then) owner who lived in Marshall TX, and, conveniently, worked behind the parts counter at the local Chev dealership. It was assembled at Muncie IN in 1971, April 19th. Notice the number 43265 above. I believe this indicates it was not installed initially in a General Motors vehicle, and the number was to be recorded for warranty purposes.

I believe that the Muncie plant was assigned a block of numbers each year to be stamped on the units that were to be shipped for service, and that for trannys, they started at (say) 35000 and counted up from there. I don't recall where I heard this, but sounds logical. Any commentsf welcome.

By coincidence, the 43265 stamping is also the last 5 digits of my VIN (23564) but scrambled .

[Joe L.]

Re: M22 Service (over-the-counter) transmission

This was installed in 1971 or 2 in my '65 396 by the (then) owner who lived in Marshall TX, and, conveniently, worked behind the parts counter at the local Chev dealership. It was assembled at Muncie IN in 1971, April 19th. Notice the number 43265 above. I believe this indicates it was not installed initially in a General Motors vehicle, and the number was to be recorded for warranty purposes.

I believe that the Muncie plant was assigned a block of numbers each year to be stamped on the units that were to be shipped for service, and that for trannys, they started at (say) 35000 and counted up from there. I don't recall where I heard this, but sounds logical. Any commentsf welcome.

By coincidence, the 43265 stamping is also the last 5 digits of my VIN (23564) but scrambled .

Wayne---


Is this a 1966-70 style Muncie or a 1971-74? The differences are 10 spline versus 26 spline input (which, of course, can't be seen with the trans installed) and 26 versus 32 spline output. The easiest way to tell is by the casting number on the extension housing.

[Larry E.]

Re: M22 Service (over-the-counter) transmission

FWIW: I once talked to Alan Colvin (Years Ago) and he indicated that he has all the accurate dates
of manufacture of M22's at the Muncie Plant. AFAIK he has never shared this info with anybody from
the NCRS. Larry

[Wayne M.]

Re: M22 Service (over-the-counter) transmission

Is this a 1966-70 style Muncie or a 1971-74? The differences are 10 spline versus 26 spline input (which, of course, can't be seen with the trans installed) and 26 versus 32 spline output. The easiest way to tell is by the casting number on the extension housing.

Joe ---here's a shot of the "extension housing casting no." Excuse the focus, but I was shooting blind lying on the garage floor. The casting # is "38557584GM", (per the photo) indicating a mainshaft with 27 output spine teeth. I can't verify the input (clutch) gear as the trans is still in the car [and has been for the last 29 years that I've owned it]

BTW, I checked the maincase casting # and it's 3925661.

[Larry E.]

Re: M22 Service (over-the-counter) transmission

Wayne: What starter number is in the car? Can you confirm it is a 10.5 clutch and not the 11"?? Larry

[Joe L.]

Re: M22 Service (over-the-counter) transmission

Wayne: What starter number is in the car? Can you confirm it is a 10.5 clutch and not the 11"?? Larry

Larry------


All 1965 L-78 originally were equipped with a 10.4" clutch. All one needs to do to confirm this is to check the bellhousing number. 383 or 403 it's 10.4"; 621 it's 11"

[Joe L.]

Re: M22 Service (over-the-counter) transmission

Joe ---here's a shot of the "extension housing casting no." Excuse the focus, but I was shooting blind lying on the garage floor. The casting # is "38557584GM", (per the photo) indicating a mainshaft with 27 output spine teeth. I can't verify the input (clutch) gear as the trans is still in the car [and has been for the last 29 years that I've owned it]

BTW, I checked the maincase casting # and it's 3925661.

Wayne-----

Input shaft is not important. Since this is a 1971 transmission, I was just curious if someone had converted to the 71-74 Muncie. This is often regarded as the "heavy duty" Muncie regardless of M-20, M-21, or M-22 because of the increased size of the output shaft. So, some guys want to convert to that. It does require shortening or replacing the driveshaft, replacing the transmission yoke, and, if the driveshaft is not replaced, using conversion u-joints at the rear end (or, changing the companion flange).

But, it looks like you have the 66-70 style Muncie with the 1970 main case.

[Wayne M.]

Re: M22 Service (over-the-counter) transmission

Larry -- right now my 396 convertible has a small block starter 1109065 8_C_13, which I swapped, with a 1107320 5_B_15, which I then installed {the latter} in my L76 '65 coupe just before selling it a few years ago. The 396 has the "403" bellhousing, with near total orange paint coverage [less than half remaining after 53 years].

[Tom D.]

Re: M22 Service (over-the-counter) transmission

Retired Parts counter people, or GM SPO folks: What do you know about the practice of a serial number on service parts? Does it relate to the practice of numbered service engine assemblies? Was it done on service transmissions? (I'm sending this to Don Griffin also.)

[Wayne M.]

Re: M22 Service (over-the-counter) transmission

A bit more info on my April 19th 1971 service M22 in my 396. Sidecover seems to have the correct casting # for 1970 and up Muncies (3952 648) with a space between the 2 and the 6, and the 8 barely visible). AFAIK, these had the cast boss on the 3-4 gear shaft, I think used for a switch controlling vacuum advance when in 4th gear, after a certain number of seconds following the shift.

Notice in my case,the boss is cast, but not drilled/tapped for a switch.

[Michael M.]

Re: M22 Service (over-the-counter) transmission

Retired Parts counter people, or GM SPO folks: What do you know about the practice of a serial number on service parts? Does it relate to the practice of numbered service engine assemblies? Was it done on service transmissions? (I'm sending this to Don Griffin also.)

I'm not a retired parts guy, just an old GMAD and car guy (Fremont '65-82). The pic below is from the Camaro Research Group website and quotes from a Service Bulletin on service engines and transmissions. The stamp in the pic above follows the Muncie number block but does not have the T or year stamp described in the bulletin. Maybe the Muncie people figured it was obviously a transmission and the year was included in the P1D19C stamp.

[Ronald L.]

Re: M22 Service (over-the-counter) transmission

Wayne - these early Muncie were JUNK, the main cases froze on input shafts, broke etc. Usually if you went up to a 661 you would be with a later side cover because the 65 had smaller stuff. If the tail shaft is proper 65 dated that its a higher probability all that happened was a main case change, so typical to these cars that were run hard in the late 60/ early 70's

[Ronald L.]

Re: M22 Service (over-the-counter) transmission

Wayne - since you wrote this I have seen no less that 5 examples of these 43xxx type coding on muncies