If you have a later Plymouth and were curious - these are lists of all the sales codes they used. I think they go back to 1982 or so; they might even go back to the late 1970s, I haven't done enough research to be sure. The transmission list is of course much shorter!

https://www.motales.com/cars/materials/sales-codes.php

https://www.motales.com/engines/transmissions/index.php

It's kind of off topic but while we're here, this is where I keep articles showing Plymouth and other Chrysler Corp ads, brochures, press releases, and such... :
https://www.motales.com/chrysler-corp/ycats/lit.php

Some of that film has been spliced from earlier takes.

I have my engine and tranny out for a rebuild and wanted to paint them the correct color.  Most of what I found on-line state that the engine and bell housing were assembled and installed as a unit.  Therefore they were painted the same color which was silver.  However, I did find this really cool video of the production of a 1939 Plymouth:
 
https://youtu.be/t2meFtVHIOQ

At 5:32 minutes into the video you can see the assembled engines, the heads look silver but the blocks and bell housings look a different shade (the video is black and white). At 5:46 the engine is installed and it looks to be entirely silver. The car in the video is a 4 door sedan and not a convertible, but I would figure all engines would be the same color.  Can anyone out there confirm the color of the engine and bell housing for me? 

Thanks in advance - Jerry

The wheels on the newly acquired 30U were locked up and after trying to release them manually there were still a couple of locked wheels. I winched it on the trailer and later, after removing the wheels, I found that the shoes, while oriented correctly with long lining forward (Lockheed), were not mounted uniformly in that the shoes were mounted differently at the anchor. 

Early brake shoes have a boss/lip standing up at the anchor end (Pic #1 shoe. The brake anchor support appears to be formed so that the brake shoe lip will nest into it (Pic #2 support). Some shoes were nested into the anchor and had approximately .100" clearance between the back of the shoe and the backing plate (Pic #3 clearance). Other shoes had the lip toward the backing plate and had minimum clearance. It seemed logical that the shoes should nest at the support AND require a spacer washer against the plate to fill the gap because using the lip as a spacer would create a wear point.

I searched 1929-39 parts list, the Models Prior to 1934 and a 1928 parts list and did not find any evidence of a spacer washer.

Has this subject been researched? Thanks

The production of all 1966 model year Plymouths began in August 1965 and ended in July 1966.  The scheduled build date of a vehicle will be located on a "Body Code Plate" (also known as a "fender tag") which is mounted on top of the driver side inner front fender next to the battery.  The DATE CODE will be the first three characters on the bottom row of the tag.  The first character will be the month (1 thru 9 for months January thru September or A, B, or C, for months October, November, and December) and the next two digits will be the day of the month.  For example, a date code of "C29" represents a scheduled production date of December 29, 1965.

Could it have been where an extension/accessory spare tire inflator was mounted?

This car is very original.  I don't think it ever had air shocks.

If the car had rear air shocks installed at one time, this hole could possibly have been used to mount the fill valve?

I recently bought a '50 special deluxe convertible.  It has a square hole in the rear bumper deck.  Any ideas about what might have been mounted there?

aquamarine blue used a straw color, almost cream ; not sure about the other formulas