Ford Mustang Owner's Manual page 319

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
Six-speed manual transmission (MT82)
Six-speed automatic transmission (6R80)
2012 05+ Mustang (197)
Owners Guide, 3rd Printing
USA (fus)
Maintenance and Specifications
Code
X
3
319