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68 Tranny Date Code Question

Old Dec 23, 2018 | 09:02 AM
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Default 68 Tranny Date Code Question

Help me find the suffix. The Judging Guide shows A B or C as possible suffixes. The only suffix I see is a symbol - not a letter, and is clearly stamped. .
FYI- The car is a March 21 build date.


This is the date code as appearing on the transmission:



Thank you
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Old Dec 23, 2018 | 09:07 AM
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I'm guessing there was a broken B in the gang stamp.
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Old Dec 23, 2018 | 10:52 AM
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to correct the info. the code identifies the source, model and date the tranny was built. it does not identify the dates that the parts and the cases were cast and machined.
ballpark, that date should be 2 weeks to 3 months prior to the car's birthday.

my book states they did NOT affix the A B or C to the 68 and not start that until they were into the 69 year. so dont know what that last character is since it disagrees with the attachment above from the OP...

Last edited by joewill; Dec 27, 2018 at 10:51 AM.
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Old Dec 23, 2018 | 11:11 AM
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Default Agree!

[[b]QUOTE=joewill;1598550779]to correct the info. the code identifies the source, model and date the tranny was built. it does not identify the dates that the parts and the cases were cast and machined.
ballpark, that date should be 2 weeks to 30 months prior to the car's birthday.

my book states they did NOT affix the A B or C to the 68 and not start that until they were into the 69 year. so dont know what that last character is since it disagrees with the attachment above from the OP...



Agree, no suffix on 68 Muncie. You might still have the little sheet metal tag on one of the cover bolts, if so, check the 68 AIM and the number will tell you M20 or M21. Or you can shift it into first and count the rotations.

That mark is a casting (?) mark of some kind, maybe to hold the casting or casting numbers some kind of way. We all hope that was a "C", but sorry not likely so. I had this casting mark on my 68 and your question was asked before. The casting mark in your photo matched mine, the other posters question and your photo. I do agree however, it does look like it was stamped, if so, I do not know the meaning.

Hope this helps.

Merry Christmas and Happy New Year!!!

I have a photo of my 68 Muncie that matches your casting mark and will post, but have find it first, ha! The last place I looked as always!



Last edited by 20mercury; Dec 23, 2018 at 11:33 AM.
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Old Dec 23, 2018 | 11:53 AM
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Thanks, all I appreciate your input. So my judging guide is wrong where it states there was a suffix after the date code?
I tried to locate the tag in the judging guide, but cannot find it.
My tag:



This link is an old cf post stating the number on my tag is for an M-21

https://www.corvetteforum.com/forums...post1552216330

Does your judging guide agree?

Thank you
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Old Dec 23, 2018 | 07:40 PM
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I would send that picture over to Paul Cangialosi
http://www.5speeds.com/
He is the last word in Muncie Transmissions.
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Old Dec 23, 2018 | 11:12 PM
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I emailed Paul and he got back to me. He says 68 Muncie transmissions have no suffix after the date code. Thanks for the suggestion.

Now, is my tag telling the truth?
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Old Dec 24, 2018 | 03:44 AM
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All of my sources show that 3915090 tag is an M-21 for a 1968 Corvette L79
Looks good to me.
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Old Dec 24, 2018 | 11:33 AM
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Originally Posted by cor66vette
I emailed Paul and he got back to me. He says 68 Muncie transmissions have no suffix after the date code. Thanks for the suggestion.

Now, is my tag telling the truth?
You should clarify that statement just a little more. For the 1968 model run year there was no suffix after the date. At some point in late 1968 for the 1969 model run they started putting the letter at the end. I have a M20 built Dec 6 1968 that has the letter on the end. I am not sure exactly when they started adding the letter.
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Old Dec 24, 2018 | 01:16 PM
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Default Agree!

Originally Posted by Greg
All of my sources show that 3915090 tag is an M-21 for a 1968 Corvette L79
Looks good to me.

Agree, here is the sheet out of the 68 AIM.

Merry Christmas and Happy New Year to ALL!!




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Old Dec 27, 2018 | 09:21 AM
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I sent a copy of the page from my 4th EDITION judging guide (picture 1 of 2 in my opening post) to Paul Cangialosi. His response was a simple, "The guide is wrong".
Just for shitzngiggles, has it been corrected in the 5th EDITION ?
I trust Paul's to be the more accurate information.
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Old Dec 27, 2018 | 10:50 AM
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yup, drives me nuts that lawsuits are threatened and filed based on what's in that judging guide.... written by non professionals that make no money volunteering for a non profit organization...
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Old Dec 27, 2018 | 02:30 PM
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^ ^ ^ You know? I never looked at it that way.
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Old Dec 27, 2018 | 04:01 PM
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66

The suffix codes to denote what type of Muncie transmission it is didn't start until early in the 69 model year. The character you show appears with some regularity at the end of Muncie transmission codes for 1968. To my knowledge it is not known what it means, Attached are a couple more picture of the same character on 68 Munice transmissions taken from the NCRS website.

John




Last edited by JC68; Dec 27, 2018 at 04:11 PM.
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Old Dec 27, 2018 | 09:20 PM
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Do you care if I steal a few of these pictures? You just never know, maybe when the 6th Edition of the 68-69 NCRS TIM&JG is released, one might appear in it with the error of our ways corrected. We know a lot about these cars, but we don't know everything. Almost everyday I learn something new. Post's like this just makes things better...
Gb
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Old Dec 27, 2018 | 10:46 PM
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Paul Cangialosi.says that symbol after the date code is an inspection stamp.
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Old Dec 28, 2018 | 01:43 PM
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Default Much Thanks!

Originally Posted by cor66vette
Paul Cangialosi.says that symbol after the date code is an inspection stamp.
Finally mystery solved!!! Much thanks!! Another "how is the 68 Corvette different?" question answered.

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