My First Post-3877459 Transmission Tag
I am about to purchase my very first Corvette, a 1966 427/425 HP Convertible. I am not an expert and have spent hours trying to research the car. The engine and transmission are supposedly original (yeah, I know). I assume that it's an M20 or M21 based on the 3885010, 3857584, 3884685 casting numbers. My problem is the 3877459 transmission tag. After 2 1/2 hours of research, it appears that tag number is for a '66 Chevelle. Can someone here offer some guidance? And yes, I am meeting with an appraiser at the car prior to purchase; I just want to be as knowledgeable as possible prior to inspecting the car. Also, how much would this hurt the value of the car if it isn't original?
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Re: My First Post-3877459 Transmission Tag
George - found this ref 3877459 - hope you can paste the link in - not sure if there's a way to ID a transmission as trans tags could easily be changed , just a thought ?
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Re: My First Post-3877459 Transmission Tag
George,
Welcome to one of the most informative Corvette Forums. In 1966 the big block Corvette only came from the factory with the M21 close ratio transmission and the tag number would have been 3880855. As far as I know, both the M20 and the M21 had the same main transmission casting number (3885010)...the difference is in the guts. With that being said, it would depend on the condition of the rest of the car and the individual buying as to how the value would be effected. M21 transmissions are available as are the tags. Again, it depends where you want to go with the car.Leif
'67 Coupe L79, M21, C60, N14, N40, J50, A31, U69, A01, QB1
Top Flight 2017 Lone Star RegionalComment
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Re: My First Post-3877459 Transmission Tag
George,
Welcome to the NCRS!
The numbers for the casting is correct for a 1966 Muncie Trans. however the 425 should have an M-22 with a tag number of 3879987 or an M-21 with a tag number of 3880855. Both are close ratio transmissions. Don't tell anybody it's a M-22 and use the M-21 tag. Don't think many M-22 were in 66 425HP Corvettes.
You can get tags from Long Island Corvette Supply 1 800 466-6367 for $25.00 Online at www.licorvette.com
JRComment
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Re: My First Post-3877459 Transmission Tag
Is the VIN of the car stamped on the trans.? That will determine whether or not the trans. is original to the car. Tags are easily changed and mean nothing regarding originality.Comment
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Re: My First Post-3877459 Transmission Tag
Jim, thanks for the reply. I don't have a pic of the VIN stamp on the trans and it is back at the body shop getting a blemish repaired. I will be able to confirm that when I see it in person on the 29th.Comment
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Re: My First Post-3877459 Transmission Tag
Thanks for the quick reply Keith. Your reference is very helpful. Based on what I just read, it appears that my assumption that it's an M20 is probably incorrect; IF the tag is correct, its an M21 which makes more sense from what the other posters have already shared.Comment
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Re: My First Post-3877459 Transmission Tag
Thanks for the info and tag lead Joe. I'm leaning towards it being an M21 based on your info and additional research. I'm really trying to do my due diligence as I've saved 40 years for this car.Comment
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Re: My First Post-3877459 Transmission Tag
George,
Stamping the SN on the side of the transmission is not a problem. If that's all it's missing just get the tag and stamp it.
JRComment
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Re: My First Post-3877459 Transmission Tag
I've researched this quite a bit and can offer my opinion. Both the 3880853 and 3880855 tags are reported with '66 L72 M21s. One source suggests that these M21s were all the same, L79 or L72 etc, and the different tag numbers related to some of the drive gears for different diff ratios. In one section the AIM lists the 855 with the L72 but in the G81 posi page (sheet A1) the 853 tag shows as being used with L72 having 3.70/4.11 diff ratio. My L72 has the original driveline (in my opinion) and has a 3880853 tag which goes along with having the FB rear end (4.11 ratio). Anyway, as others have noted the tags are easily changed but the cast numbers which you have noted are helpful and the partial VIN stamped on the case along the with P (date) code certainly can help clarify (again just my opinion). Examples of my trans tag, VIN and P code stamps are in the photos below. Yes some people have faked trans cases but real 50 year old stamps have that certain patina! Good luck with your eval
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Re: My First Post-3877459 Transmission Tag
JR brings up a good point Maybe rather than my just focusing on the transmission, I should get your overall opinion of the totality of the car:
Here's the link
I'll be in it for $85,000 plus shipping. Thoughts?Comment
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Re: My First Post-3877459 Transmission Tag
I see the seller uses the phrase 'numbers matching' which used to mean the original factory installed components. Today it's almost a warning that it's half decent restamps.
Unless values have taken a tumble, $85K is way low for a real '66 427/425.
I'd have a Corvette expert inspect the car if originality is important.Comment
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