Author Topic: 69 Muncie Transmission tag (pn?)  (Read 2382 times)

69Z28-RS

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69 Muncie Transmission tag (pn?)
« on: January 08, 2014, 04:32:21 AM »
The following tag is on the Muncie transmission (M20) in my '69 Z.. which I believe to be totally original.  can someone confirm this is correct for a '69 Muncie M20?  I think the PN reads:   3946797...
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
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6667ss138

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Re: 69 Muncie Transmission tag (pn?)
« Reply #1 on: January 08, 2014, 05:20:45 AM »
Yes, that is the correct M20 tag
Len H.  Kansas
1969 Z/28 07A X77D80 Hugger Orange/Black Vinyl Top, born with drive train, complete 3 owner history.
1967 Chevelle SS396 138 Convertible/Red/Black int.
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1968RSZ28

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Re: 69 Muncie Transmission tag (pn?)
« Reply #2 on: January 08, 2014, 06:36:18 AM »
Gary,

Isn't the partial VIN stamped on the case?

Paul

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Re: 69 Muncie Transmission tag (pn?)
« Reply #3 on: January 08, 2014, 05:48:40 PM »
Paul,

Yes, the VIN is stamped along with the application code and the transmission is original, but I didn't know about the tag itself (although most of these were tossed away and back in the '70's when I bought this car, no one would have put one on that didn't belong.  I believe this transmission has never had the side cover off....  car has 75K or so miles (thru 1980..  not driven since).

bcmiller

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Re: 69 Muncie Transmission tag (pn?)
« Reply #4 on: January 23, 2014, 02:43:02 AM »
Gary, what ratio rear axle do you have?  The normal 3.73?  That part number was used for 3.55, 3.73 and I think 4.10 in 1969.
1968 Camaro SS 396 - now 468 BBC, M21, 12 bolt.
Looking for 68 Camaro with body number NOR 181016
Bryon

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Re: 69 Muncie Transmission tag (pn?)
« Reply #5 on: January 23, 2014, 02:43:42 AM »
Yes, rear is a BU (3.73:1 ratio)...

69Z28-RS

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Re: 69 Muncie Transmission tag (pn?)
« Reply #6 on: May 08, 2014, 12:53:42 PM »
There's a 'Muncie transmission tag' for sale on ebay
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=161298278028&ssPageName=ADME:B:SS:US:1123

This one is identified as  "1969 Chevelle, Corvette, Camaro Muncie M20 Factory Original Trans Tag 3950356".   This is  different number than on my original M20 Muncie.

Based on bcmiller's post below, were different PN's used on Muncies based on the *rear end ratio*??  Why would they do that??
(I'm trying to learn my 'Camaro new information for the day'...  :)

jdv69z

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Re: 69 Muncie Transmission tag (pn?)
« Reply #7 on: May 08, 2014, 01:38:05 PM »
Here's my M20 Tag
Jimmy V.

jdv69z

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Re: 69 Muncie Transmission tag (pn?)
« Reply #8 on: May 08, 2014, 01:41:39 PM »

Based on bcmiller's post below, were different PN's used on Muncies based on the *rear end ratio*??  Why would they do that??
(I'm trying to learn my 'Camaro new information for the day'...  :)

Because each different rear end ratio required a different plastic (I think) gear to make the speedometer read correctly.

69Z28-RS

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Re: 69 Muncie Transmission tag (pn?)
« Reply #9 on: May 08, 2014, 02:02:19 PM »
Thanks!!   :)    That makes sense..    !   :)

JohnZ

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Re: 69 Muncie Transmission tag (pn?)
« Reply #10 on: May 08, 2014, 04:36:58 PM »

Based on bcmiller's post below, were different PN's used on Muncies based on the *rear end ratio*??  Why would they do that??
(I'm trying to learn my 'Camaro new information for the day'...  :)

Because each different rear end ratio required a different plastic (I think) gear to make the speedometer read correctly.

Actually, the plastic DRIVEN gear was installed at the car assembly plant. What changed was the internal steel DRIVE gear that was pressed on the output shaft at Muncie; there were two different diameter steel DRIVE gears that only worked with two different "families" (diameters) of plastic DRIVEN gears, depending on the axle ratio, and the transmission assembly part number on the steel tag was the only way Muncie or the car assembly plant could tell which transmission they had.
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jdv69z

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Re: 69 Muncie Transmission tag (pn?)
« Reply #11 on: May 08, 2014, 06:48:50 PM »
So there were 2 diff parts no.s for each of the 3 trans - M20, M21, and M22?

ko-lek-tor

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Re: 69 Muncie Transmission tag (pn?)
« Reply #12 on: May 08, 2014, 07:17:32 PM »
All covered in the AIM- M20-A1 I had asked about this sometime back about the difference in the part numbers for different RPO's. M20 was either 3950356 or 3946797 for 1969 depending on RPO and Gear ratio. Might as well put other #'s while I am looking at page-M21= 3950316 or 3946798, M22-3950318
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69Z28-RS

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Re: 69 Muncie Transmission tag (pn?)
« Reply #13 on: May 08, 2014, 07:19:51 PM »

Based on bcmiller's post below, were different PN's used on Muncies based on the *rear end ratio*??  Why would they do that??
(I'm trying to learn my 'Camaro new information for the day'...  :)

Because each different rear end ratio required a different plastic (I think) gear to make the speedometer read correctly.

Actually, the plastic DRIVEN gear was installed at the car assembly plant. What changed was the internal steel DRIVE gear that was pressed on the output shaft at Muncie; there were two different diameter steel DRIVE gears that only worked with two different "families" (diameters) of plastic DRIVEN gears, depending on the axle ratio, and the transmission assembly part number on the steel tag was the only way Muncie or the car assembly plant could tell which transmission they had.

Thanks JohnZ... :)    you came thru with factual 'new information' for the day ..  AGAIN..  :)

*(and Bentley).*  You posted while I was typing.. :)

jdv69z

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Re: 69 Muncie Transmission tag (pn?)
« Reply #14 on: May 08, 2014, 07:53:47 PM »
So I'm assuming the M22 was only available over a narrow range of rear end ratios, thus only needing 1 part no.?

z28z11

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Re: 69 Muncie Transmission tag (pn?)
« Reply #15 on: May 09, 2014, 02:09:21 AM »

Based on bcmiller's post below, were different PN's used on Muncies based on the *rear end ratio*??  Why would they do that??
(I'm trying to learn my 'Camaro new information for the day'...  :)

Because each different rear end ratio required a different plastic (I think) gear to make the speedometer read correctly.

Actually, the plastic DRIVEN gear was installed at the car assembly plant. What changed was the internal steel DRIVE gear that was pressed on the output shaft at Muncie;

Actually not pressed on, the gear slips over the tail end of the mainshaft and is secured by a spring steel clip. How do I know ? My '69 Z M20 clip broke, lodged in the reverse gear, and jammed the transmission. I made it to the station I worked at, pulled the trans and found the problem. New clip and back in business. Earlier Muncies pressed on -  
« Last Edit: May 09, 2014, 03:15:22 AM by z28z11 »
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JohnZ

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Re: 69 Muncie Transmission tag (pn?)
« Reply #16 on: May 09, 2014, 05:28:26 PM »

Based on bcmiller's post below, were different PN's used on Muncies based on the *rear end ratio*??  Why would they do that??
(I'm trying to learn my 'Camaro new information for the day'...  :)

Because each different rear end ratio required a different plastic (I think) gear to make the speedometer read correctly.

Actually, the plastic DRIVEN gear was installed at the car assembly plant. What changed was the internal steel DRIVE gear that was pressed on the output shaft at Muncie;

Actually not pressed on, the gear slips over the tail end of the mainshaft and is secured by a spring steel clip. How do I know ? My '69 Z M20 clip broke, lodged in the reverse gear, and jammed the transmission. I made it to the station I worked at, pulled the trans and found the problem. New clip and back in business. Earlier Muncies pressed on - 

Yup - the nylon DRIVE gear and spring steel retainer started in '68.

Bryan302

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Re: 69 Muncie Transmission tag (pn?)
« Reply #17 on: Today at 05:32:58 AM »
I'm in the process of rebuilding / restoring my M21.  I'm to the point of refinishing the bolts and the 3946798 part number tag and wanted to find out what finish the part number tag was originally?  Was it natural bare steel and painted or zinc plated?

Thanks,
Bryan
Bryan S.
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ko-lek-tor

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Re: 69 Muncie Transmission tag (pn?)
« Reply #18 on: Today at 12:00:49 PM »
I'm in the process of rebuilding / restoring my M21.  I'm to the point of refinishing the bolts and the 3946798 part number tag and wanted to find out what finish the part number tag was originally?  Was it natural bare steel and painted or zinc plated?

Thanks,
Bryan
Bryon, I am going to stick my neck out, based on my observations over the years and, think about it, these tags were for the line workers to ID a trans, why would they (Muncie Div., GM) require paint or plating (adding uneccessary costs)? So, I have only observed plain unpainted/ unplated steel stamped tags and I am sure that is how they came. B.

69Z28-RS

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Re: 69 Muncie Transmission tag (pn?)
« Reply #19 on: Today at 12:24:41 PM »
I'm in the process of rebuilding / restoring my M21.  I'm to the point of refinishing the bolts and the 3946798 part number tag and wanted to find out what finish the part number tag was originally?  Was it natural bare steel and painted or zinc plated?

Thanks,
Bryan
Bryon, I am going to stick my neck out, based on my observations over the years and, think about it, these tags were for the line workers to ID a trans, why would they (Muncie Div., GM) require paint or plating (adding uneccessary costs)? So, I have only observed plain unpainted/ unplated steel stamped tags and I am sure that is how they came. B.

I'm usually with Bentley, and I am here as well... I've never observed any traces of paint or plating on those tags; most are covered in light rust when going untouched.  Suggestion:  evaporust and then a light coast of satin clear should preserve it looking 'new' for a long while.. :)

bcmiller

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Re: 69 Muncie Transmission tag (pn?)
« Reply #20 on: Today at 01:56:07 PM »
We have agreement.  Those metal tags were natural metal, not painted or plated.   :)