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Topic: Is there a way to identify an M22 without removing it?

in Forum: C3 Driveline Components


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Is there a way to identify an M22 without removing it? (1/10)
 5/10/08 4:02pm
dmerrill
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Sunrise Beach, MO - USA

Vette(s):
1971 454 4-speed Stingray


Joined: 5/10/2008
Posts: 10

Hi, I am new here and in the process of getting my 1971 Stingray out of a 13-year hibernation. I was told long ago that I have an M22 tranny, but given the very small number that were made, I have doubts. Is there a way to tell without taking it out of the car? I need some rear body work done and am extremely hesitant to hand it over to a shop given that I might have that very rare tranny.
 
On the other hand, I am the 3rd owner and have had it since it was only 14 years old, so maybe I do, maybe I don't. Any help would be greatly appreciated!
 
Thanks!
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Is there a way to identify an M22 without removing it? (2/10)
 5/10/08 5:00pm
Ten15
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East Hanover, NJ - USA

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'68 Black Conv. Matching 327/300 4 Spd. P/S, P/B, P/W, Tele, A/C


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Dawn,
 
Most (probably all) Muncie transmissions from 1969 on were stamped "A" for the M-20, "B" for the M-21, or "C" for the M-22.
 
From the outside, all of the Muncie cases are the same.  Only the M-22 was tapped for a drain @ the factory. 
 
The letter will follow the date stamp production code on the passenger side of the tranny.  The VIN derivative is also stamped in this area.
 
An example of a February '71 M-20 stamping would be "P1B13A" 
P= Muncie
1= 1971  
B=February
13 = 13th day
A= M-20
 
Hope this helps,

Anthony
 
Is there a way to identify an M22 without removing it? (3/10)
 5/10/08 6:01pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


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If the car is drivable, determining the trans is an M22 is easy...just listen for the noise! They growl quite loudly in all gears.
You could also remove the side/shifter cover, and look at the gears. M22 gears are almost straight-cut...very little angle to them.
While it's true that the M22s had drain plugs..other transmissions did also, so that, in itself is not the determining factor.
The stamp numbers, and a look at the gears themselves is really the only way to know for sure what it is.

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Is there a way to identify an M22 without removing it? (4/10)
 5/10/08 7:15pm
dmerrill
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Sunrise Beach, MO - USA

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1971 454 4-speed Stingray


Joined: 5/10/2008
Posts: 10

Thanks guys! We will have a look at the case and go from there. I'll keep you posted :)

Dawn
Is there a way to identify an M22 without removing it? (5/10)
 5/10/08 7:30pm
dmerrill
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Sunrise Beach, MO - USA

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1971 454 4-speed Stingray


Joined: 5/10/2008
Posts: 10

Oh, and as for the noise, it's been so long I can't truly remember. What I do remember is missing a gear badly in a street race about 20 years ago. My boyfriend told me it should have shredded the gears, but there was no apparent problem :)
 
Dawn
Is there a way to identify an M22 without removing it? (6/10)
 5/10/08 9:15pm
dmerrill
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Sunrise Beach, MO - USA

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1971 454 4-speed Stingray


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Posts: 10

Gentlemen, where exactly is the tranny stamp? I crawled under but there is a lot of built up grease. Right now we are replacing fuel lines, so it's a great time to look :)
Is there a way to identify an M22 without removing it? (7/10)
 5/10/08 11:53pm
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


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Look in This area for the trans ID stamp. It may be on the driver side, the pass side, or even the top or bottom, but the most common place is driver side, right where I've marked this one.

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Is there a way to identify an M22 without removing it? (8/10)
 6/1/08 7:22pm
dmerrill
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Sunrise Beach, MO - USA

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1971 454 4-speed Stingray


Joined: 5/10/2008
Posts: 10

Well gentlemen, it appears I have an M-21, disappointing but not wholly unexpected once I realized how few M-22s there were. Here is the stamp:
 
P1A22BH
 
at least it looks like an H at the end. There did appear to be drain plugs though.
 
Sorry it took so long! Just got the brakes fixed, it is nearly ready to actually drive, woohoo!!
 
Dawn
Is there a way to identify an M22 without removing it? (9/10)
 6/1/08 7:28pm
Ron 78Lifetime Member
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Like Joel said,You'll know if you've got a Rock Crusher,you can hear em a mile away LOLLOLLOL

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Is there a way to identify an M22 without removing it? (10/10)
 6/1/08 9:25pm
dmerrill
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Sunrise Beach, MO - USA

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1971 454 4-speed Stingray


Joined: 5/10/2008
Posts: 10

I'm ok with an M-21 though :) It sure felt good to be back behind the wheel, even just around the block!!
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