C2 M20 transmission date stamping

[Barbara S.]

I hope someone can help me with a couple of questions regarding the date stamping of an M20 Muncie transmission for 1965.

1. When was the transmission date stamped in relationship to the date stamping on the engine stamping pad? Was the engine stamped before or after the tranny was date stamped?

2. How should the alpha-numeric date stamping read for a tranny dated July 14, 1965? According to the JG, the letter P should be first. Should it read: P5G14?

Thanks for any help.
Tony

[Joe L.]

Re: C2 M20 transmission date stamping

Tony-----

1) The transmission was date-stamped at Muncie, IN transmission manufacturing plant at the time of assembly. The engine was date-stamped at the engine plant at the time of its assembly. Other than the fact that both dates should precede the assembly date of the car, there is no relationship between the 2 dates. The VIN derivative stamping on the engine and transmission were performed at approximately the same time at St. Louis;

2) No alpha character was used for 1965 Muncie date codes. So, the date code for a July 14 transmission would be P 0714. The year was also not coded into the series; just the month and day.

[Barbara S.]

Re: C2 M20 transmission date stamping

Thanks Joe for the clarification.
Tony

[Wayne M.]

A few other points

Joe L. is correct in his reply about VIN and assy. date format and sequence / location of stamping.

If this is a tranny that you are looking at as a candidate for a mid-July 1965 production car, I have to say that all "probable" originals have assembly dates no later than P0630 (June 30th). It's as if there was a huge batch with that date stored at Munce IN that were shipped to St.Louis as required during the month of July. Even in Noland's Vol 2, none of the late cars have a July trans assy date (except one with July 26th, which would have been a stretch to ship and install on VIN 23530 (July 30th [Friday] or 31st). There are Muncies with date stamps throughout July and into mid-August, but they were shipped to other Chev or BOP assembly plants that continued to produce until late August 1965.

If this is a virgin maincase that you are thinking of stamping, make sure it is not a later "325" replacement, made from the same mould as the "660 / 661" series (has the wide pass. side stamp pad, and unusually weak part # casting).

Also, remember that 1965 St.Louis VIN stampings were of format S123456, and not 5123456 (changed sometime after fall 1964 strike). In other words, it differs from the engine block format, and also from the '66 / '67 trans format 6S123456 etc. Finally, if re-stamping, make sure the characters face the typical direction for that production timeframe.