Try these links.
http://www.gmheritagecenter.com/gm-heritage-archive/vehicle-information-kits.html, click on show.
1955 2nd spec PDF page 60
Parking brake mechanical, Looks like Manual & Hydra-Matic tranny had same Parking brake. Drum on Propeller Shaft.
Hydra-Matic transmission identification model guide PDF page 12 & 13, 1940-1956, Cannot find CHT, T might be an error.
You could call these guys ask for John.
Northwest Transmission Parts Give them the cast numbers on the side and CHT 55.
If you look at spec sheet
PDF page 6 it shows location of tranny tag,
Automatic Left side at (lower) Rear of center case. Also check spec.
PDF page 85, Truck Automatic Transmission
Note: The 1955 2nd spec PDF also has 1955 1st series spec. check
PDF page 200 for 1955 1st Truck Automatic Transmission.
The 1955 2nd spec Automatic Transmission page did not scan well.
Thanks,
