FORD 2005 Mustang v.2 - Manual (Page 235)

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
F Five-speed manual (T5)
K Five-speed manual (TR3650)
L Five-speed automatic (5R55S)
2005 05+ Mustang (197)
Owners Guide (post-2002-fmt)
USA (fus)
Maintenance and Specifications
235