The Classic Thunderbird Club International (CTCI) has technical information for 1955-1957 Thunderbirds on their website > Gil’s Garage.
The VTCI has a good Forum for all years of Thunderbirds. One of our longtime members is the moderator for the 55-57 sections as “Joe Johnston” on the forum. The forum is free to join and there may be some info members could use no matter the year of their car. Click Here.
I found this link for the automatic transmission manual online. May be useful to someone.
J
https://www.scribd.com/document/521825832/1956-1957-Fordomatic-Transmissions