Ford 2003 Mustang Workshop Manual page 2747

18. Install the bolts.
19. Install the output shaft rear bearing cup.
20. Install the reverse gear shift rail.
Align the ball stud with the slot in the case and align the reverse gear shift rail with the
reverse shift fork. Once the ball stud enters the case, rotate the reverse gear shift rail
until the ball aligns with the reverse gearshift lever. Rotate the reverse gear shift rail
counterclockwise until the ball stud fully engages the reverse gearshift lever.