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Author Topic: Muncie ID ?  (Read 2612 times)
69Z28-RS
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« on: April 26, 2013, 10:01:11 AM »

Attached is a photo of a stamped code on a Muncie trans I have had since 1971.  It seems to be stamped P8D10c, although the 'c' is very small....  Does anyone recognize this stamping to identify it?  I've always believed this trans to be an M22; it has the 'whine', although it's been so long that the side cover has been off, I don't recall even looking at the angle on the gears.   Has anyone else seen a 'c' stamped like this?
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
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Ed Bertrand
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« Reply #1 on: April 26, 2013, 10:07:34 AM »

P8D10 is the date code (April 10th, 1968). The square looking "c" isn't really a C, but we're not exactly sure what it was used for. The square c is pretty common on 68 Muncies, although it really looks more like the bottom half of a capital E.

You'll have to pull the side cover off to check the angle of the gears to determine if it's an M22 or not.

More info HERE.

Ed
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69Z28-RS
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« Reply #2 on: April 26, 2013, 10:51:49 AM »

thanks Ed!   I hadn't read that thread before, which addresses the odd suffixes on '67 and '68 Muncies.. Smiley
I'll pull the side cover and check the gears, and while reading thru this thread, I recalled having to change out the front case after buying the trans (which had two broken ears); and I think this stamping is on the front case.  I'll have to go check it out a bit more thoroughly.
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
69Z28
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« Reply #3 on: April 26, 2013, 12:51:31 PM »

Could it be that the gang stamp would hold so many characters and something was just put in that last slot to keep everything tight? I'm just guessing here. Maybe that square c is really an E and just not squarely stamped. Looking at some pics of Muncie stampings, they do look deep on one end and light on another end and vise versa, some way to light and some so deep it looks like they were melted in. They were all stamped by hand weren't they?
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GaryC

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« Reply #4 on: April 26, 2013, 03:42:59 PM »

Don't forget; if it is a factory original, first generation M22 the lower, forward, passenger-side main case boss was drilled and tapped for a magnetic drain plug.  While this boss could be drilled for a plug on a M20/M21 after it left the factory, if the boss is undrilled, then the case definitely was not part of a M22.

Paul
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Ed Bertrand
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« Reply #5 on: April 26, 2013, 03:52:07 PM »

Quote
Could it be that the gang stamp would hold so many characters and something was just put in that last slot to keep everything tight?

Not sure, but we have other (a lot of other) Muncies in the db without any extra characters. I'll have John weigh in on this.

Ed
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bcmiller
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« Reply #6 on: April 26, 2013, 04:59:19 PM »

I have been looking at the issue with the small c after the assembly date for several years.  It appears that it may be an inspection mark.  I have a few cases with that small squared off c and some without.  Seems like it is more common in late 68 model year assemblies.
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« Reply #7 on: April 26, 2013, 08:23:31 PM »

And in 67, some have a half-size 7 at the end of the stamped code.  The extra code may be some internal plant indicator that we'll never know why....

I will note that there are inspector stamps located on the top of the case, so that's not what these codes were used for.
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« Reply #8 on: April 26, 2013, 09:05:49 PM »

I have no idea if this has anything to do with this issue but it come to mind when I read the other thread and found the R I scratched into the mold.  Years ago I was a molder and when we got a new molder most times, if nobody knew him, they would make him mark all his casting for a while to help keep a check for quality control. I've saw initials, letters, and numbers added to molds and patterns. They could go thru scrap castings and know who put the mold up. If the new guy had a bunch in the scrap pile he had to be moved or fired. I know this sounds weird but you have to remember when this took place also. That was about the only way to keep up with who did what and after a time the identification marks would be removed.
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Daniel  
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« Reply #9 on: April 27, 2013, 06:38:43 AM »

If the input shaft has one or two rings going around the ten grooves it is not a M22.

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bcmiller
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« Reply #10 on: April 27, 2013, 02:29:29 PM »

Gary, are there any marks stamped on the top side of this case?
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1968 Camaro SS 396 - now 468 BBC, M21, 12 bolt.
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69Z28-RS
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« Reply #11 on: April 27, 2013, 03:47:50 PM »

2 grooves on the input shaft.

Only stamps on the top was a VIN (8K196xxx) and a '4' in a box near the top rear of the front case.
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
Ed Bertrand
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« Reply #12 on: April 27, 2013, 04:45:52 PM »

Two grooves is an M20. 18K196xxx indicates it came out of a 1968 Chevelle or El Camino assembled at the Kansas City, MO plant.

Ed
« Last Edit: April 29, 2013, 10:41:57 AM by Ed Bertrand » Logged
69Z28-RS
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« Reply #13 on: May 02, 2013, 12:04:14 PM »

Thanks Ed,

I cleaned it and opened the side cover; it is apparently an M20 (from the 2 grooves) although I didn't spin it and count turns.  It is NOT an M22.   
I've never ran the transmission, although I've had it since 1971; installed it briefly in a Henry J, but it was only ran once around a short block.   I let a friend use it for a few months back in the late '70's in his 55 Chevy.   All the numbers from the parts seem consistent with '68-'69 Muncie production, although I know I did swap the front case after I purchased it...  so we know the front case came from a April or May '68 Chevelle (Kansas City plant).   All visible characteristics of the trans are consistent with '68-69 Muncie M20/M21.
The ears and gears look good, and there is no damage, existing or repaired, to the transmission cases. The Chevelle VIN is stamped on the top of the transmission.  I need Camaro $$ more than I need this trans.  Do you have any idea what it's value would be?   
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
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« Reply #14 on: May 03, 2013, 07:44:32 PM »

Hey guys, on page 268 in (Chevrolet by the numbers) it states.. October 21st, 1968 a suffix letter code was added to the Muncie trans. to aid in identification.  So if the information in this book is correct no  Muncies were stamped with a A ,B or C before that date.
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" He who knows naught, knows not that he knows naught"  It's not you...  It's just the way my brain is wired.
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