Ford 2003 Mustang Workshop Manual page 2858

7. NOTE: Position the gearshift lever in third/fourth neutral position.
Using a 5/32-inch drift and a hammer, drive the roll pin downward, then remove the rear offset
shift lever.
Inspect the rear offset shift lever for wear or damage. Install a new lever as necessary.
Discard the roll pin.
8. Remove the eight bolts and carefully separate the extension housing from the transmission.