67' M21 Transmision Code Question

[Mladen Bay]

The transmission code on my February 67 is P0909. Is this correct for the car, and or is this late 66 M21. If it is correct, being that the year is not included is there any other things that have to be matched.

[Wayne M.]

if 3885010 Maincase, Sept 9th 1965 (early 66 prod)

And by this date, Muncie was already building trannys for the 1967 model year, with the new format. Assy date format for Feb '67 car would be (say) P7Bxx, or P7Axx, or any earlier month within reason. You can check for a VIN derivative stamping (opposite side of the assy date) or top forward or rear edges of maincase.

[Joe L.]

Re: 67' M21 Transmision Code Question

Mladen-----

For one thing, the transmission coding sequence you described was not used for 1967 models; that style coding was last used for the 1966 model year. 1967 used the P", followed by a numeral representing the last digit of the model year, followed by an alpha character representing the month, followed by digit(s) representing the day.

For another thing, although the date of September 9 (0909) would be within the NCRS "6 month rule" for a February-built car, it would fall outside of the normal time lapse observed.

Does the transmission have a VIN-derivative stamped on the case in the same area as the manufacturing code you described? If so, does it match the car?

[Mladen Bay]

[Joe L.]

Re: 67' M21 Transmision Code Question

Mladen-----

There were definitely some transmissions manufactured for 1967 model Corvettes that were actually manufactured in 1966; no doubt about that, at all. However, I would expect that transmissions intended for 1967 MODEL YEAR installation would have used the 1967 character sequence that I described. However, it's possible that some early-build transmissions did use the older sequence. As a matter of fact, it's a virtual certainty that any transmission built on September 9, 1966 was installed in a 1967 model year vehicle. However, since no year is included in the older manufacturing code sequence, it's also possible that the transmission was built on September 9, 1965 for installation in a 1966 model year vehicle.

There was no difference in casting numbers for the various external components between 1966 and 1967 Muncies, so the casting numbers don't provide any information useful in this case.

The best bet is to look the transmission main case over for the VIN derivative. That will "tell the tale".