Here are a couple links to separate sources (not T-Bird) that describe the 'Production Code' used on mid-50's Ford data / patent plates for various cars until mid April of '57.
https://www.1954ford.com/page3.php
https://1956-ford.com/images1956forddatacolors/1953-56-ford-car-data-plate-decode.pdf
And image 1 below from the Crown Victoria Assn website showing similar information...
In these various examples, plus the one from CTCI, the Production Code is consistently described as being: digits for the day of the month, a letter code for the month, and digits for a (presumably) daily production number.
Some of these plates have usually 2 characters between the date and daily vehicle number that is the Dealer sales area code. Image 2 below.
If you have additional or different information concerning the makeup of the 'Production Code' on this style of data/patent plate I'd welcome seeing it.
It was because of the '55/'57 Thunderbirds that much of the original Ford vehicle information from the mid/late 50's was saved.
"
While employed at Ford Motor Company, (Lois) Eminger discovered that original invoice copies were being destroyed when no longer needed. ... Eminger felt this information might be of importance to people down the road, so she asked for permission to save these copies for future reference, and permission was granted by Ford for her to do so."
https://automotivemileposts.com/tbird/tbird1957eminger.html
Yes the charts on the CTCI / Thunderbird website don't specifically include other Ford car models, but the information corresponds directly with the original Ford documents mentioned in the previous paragraph.
"...
we have Thunderbird invoices for the 1955 models after serial number 232214 and substantially all of the 1956 and 1957 models available ..."
https://www.ctci.org/invoice-sales/
FYI, approximately 99% of '55/'57 T-Birds were built in Dearborn.
.