FORD 2005 Thunderbird v.2 - Manual (Page 218)

Transmission/Transaxle code designations
You can find a transmission/transaxle code on the vehicle certification
label. The following table tells you which transmission or transaxle each
code represents.
Code Description
A Five-speed automatic (5R55S)
S
Five-speed automatic (5R55S) with Select
Shift
2005 Thunderbird (tbr)
Owners Guide (post-2002-fmt)
USA (fus)
Maintenance and Specifications
218