Another Muncie ID question

**Patrick T.** · May 16, 2000, 04:27 PM

Re: Another Muncie ID question

I've heard so many stories about M-22's. I bought an "original M-22" for $350 from a guy who said it came out of a '72 Vette. It was it good shape except for the slider sleeves and synchronizers which I replaced. I had to have a transmission shop press off the main shaft collars, and told the guy it was an M-22.

He said it WAS an M-22. Although the helical gears were cut at a realitively flat 21 degrees, the case was wrong because there was no drain plug and fine spline input shafts were only available starting in 1970.

His observation was that the aluminum cases were fragile and easily damaged, such as one of the ears breaking off from over torqueing, and were routinely replaced with another case as all of the parts were interchangeable with M-21's. How true this is up for grabs, but after I did the rebuild, what he said made sense to me. Just my 2 cents.

**Robert C.** · May 16, 2000, 05:18 PM

Re: Another Muncie ID question

Greg, Everything I see for the vin # looks correct except for the '6'. That number doesn't belong. Maybe a mistake was corrected and the 6 instead of the next number 4 was ground out, the 4 added in line and then the final five numbers. Everything else looks correct for a very early production (aug 68)car.

NCRS-Texas Chapter

**Joe L.** · May 16, 2000, 06:17 PM

Re: Another Muncie ID question

Greg-----

As Patrick mentioned, it would be very easy for the transmission main case to have been changed or for this transmission to have been made up from "mix-and-match" components. Obviously, the extension housing has been replaced which indicates that the transmission has been disassembled at least once. Since this transmission pre-dated the suffix coding system, there is no way to tell what gear set the main case originally contained.

In any event, what we can say about the main case is that it was part of a transmission assembled on August 22, 1967 for installation in a 1968 model year vehicle. Also, from the "s" in the VIN-derivative we know that the vehicle that it was originally installed in was assembled at the St. Louis, MO GM assembly plant. Understand that the St. Louis plant produced a lot more than Corvettes. In fact, at about the time that the car that originally received this transmission rolled off the assembly line, the St. Louis plant had about the largest output in the entire GM system. Vehicles produced at St. Louis at that time which could have been equipped with Muncie 4 speeds included full size Chevrolet passenger cars and Chevelles, and, of course, Corvettes.

This particular transmission was NOT originally installed in a Corvette, though. We know that by the first two digits of the VIN derivative which are "18". The "8" refers to the model year (which jives with the transmission build date). The "1" is the ONLY clue as to what vehicle that it was originally installed in and would be the last digit of the body style code. Knowing what other vehicles were assembled at St. Louis at that time, I MAY be able to decode it or, at least, narrow it down when I have access to my other references later on. Incidentally, for a Corvette, these first two digits would have been "78" for a 1968 model.

**Terry M.** · May 16, 2000, 10:08 PM

Re: Sorry Joe *TL*

Sorry to disagree Joe, but 18S400103 works just fine for a 1968 Corvette VIN derivative. What IS inconsistent here is the extra number 6. I just have never seen that on a Corvette.

Also of interest is that 1968 Corvette s/n 103 would have a body build date of about August 30 or 31. Number 94 was August 30. That would work just fine with the transmission assembly of August 22, 1967.

That extra 6 sure is a puzzle though.

Terry

**Joe L.** · May 17, 2000, 11:18 AM

Re: Sorry Joe

Terry-----

I agree that if one eliminates the "6" after the "s", then the rest of the sequence would be correct for a 1968 Corvette. However, I really don't understand the "1" before the "8" at the beginning of the sequence. On Chevrolets of this period, the last digit of the body style precedes the year designator in the VIN. For a Corvette, that digit should be a "7". The only vehicle assembled at St. Louis during that period which had a "1" as the last digit of the body style was a 2 door, full size passenger sedan. But, in that case, the first digit after the "s" should be "0" and not "4". As far as I know, the "4" in this position is correct for Corvettes only.

**Greg Moen** · May 17, 2000, 12:06 PM

Re: Sorry Joe

Let me get a picture up on the web so you can see it, that 6 is very hard to read and it may not be a 6 at all. It's the only digit that looks out of place, give me a little time and I'll get a pic up so you can look at it for yourself. The word from the guy who owned the '69 I took it out of in the early 80's claims it came out of a '68 L88 car, but you know how that goes. I don't put much stock in it, but tracking it's history is interesting.

I'll try to get a pic up by later tonight and post the URL so you can look at if for yourself.

Thanks GMan

**Robert C.** · May 17, 2000, 07:30 PM

Re: "1"

Joe, we're not talking engine pad vin stamps, we're talking trans. stamp vins. The '1' means Chevrolet.

NCRS-Texas Chapter

**Joe L.** · May 17, 2000, 08:07 PM

Re: "1"

Bob and Terry-----

Actually, as I just discovered, it's the same for the engine pad VIN derivative stamping. For years I've labored under the impression that the VIN-derivative represented the last 9 characters of the VIN. However, I now discover that I was incorrect in this assumption. Apparently, the VIN-derivative used is the first character(denoting GM Division) + the last 8 characters of the VIN. So, the four character vehicle series/model code is the only part of the VIN completely omitted on the engine/transmission/frame VIN derivative.

**Terry M.** · May 17, 2000, 08:52 PM

Re: It is not so simple *TL*

Joe, Bob et al,

It is not so simple - I can only speak for 1968-1972 Corvettes as that is where I have judged, but:

1968 = 18S4XXXXX

1969 = 19S7XXXXX

1970 = 70S4XXXXX

1971 = 71S1XXXXX AND C11S1XXXXX depending on the serial number of the car.

1972 = 12S5XXXXX

As you stated Joe, both the engine VIN derivative and the transmission VIN derivative should be the same. They were typically done by the same person with what should have been typically the same set of stamps.

Now let's not go to where it can be stamped as that gets complicated also. For what it is worth, all of the above information, and where the stamp goes, is in the NCRS Technical Information Manual & Judging Guides. Available from the home page on this site from the folks who pay for the site.

Terry

**Greg Moen** · May 20, 2000, 05:35 PM

PICS!

Sorry it took so long to get pics up but if you follow the link it will take you to them. There are a total of 9 pics numbered 'M22-1.jpg' through 'M22-9.jpg', when you get to first pic the link takes you to just replace the pic number (1-9) in you browsers address bar and you can see all 9 of them. I think the 6 is a stamping mistake and the 4 following it is hard to see on film but it is visible in person. But it does read 18s400103, the S almost looks like another 8 in the pictures. One other thing I was told is that only the Corvette had all the identification #'s are on the passenger side of the tranny like that, is this true? So now that the numbers have all been acounted for is there anyway I can find out what this came out of, and if so how? Thanks again for all the help,

GMan

Another Muncie ID question

Another Muncie ID question

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