Ford 2009 Mustang Owner's Manual page 284

Maintenance and Specifications
The Vehicle Identification Number (VIN) contains the following
information:
1. World manufacturer identifier
2. Brake system / Gross Vehicle
Weight Rating (GVWR) / Restraint
System
3. Vehicle line, series, body type
4. Engine type
5. Check digit
6. Model year
7. Assembly plant
8. Production sequence number
TRANSMISSION CODE DESIGNATIONS
You can find a transmission code on
the Safety Compliance Certification
Label. The following table tells you
which transmission each code
represents.
Description
Five-speed manual (T5)
Five-speed manual (TR3650)
Five-speed automatic (5R55S)
284
2009 05+ Mustang (197)
Owners Guide
USA (fus)
Code
F
K
L