Ford 2003 Mustang Workshop Manual page 2861

17. Remove the reverse gear thrust washer.
18. Remove the reverse gear.
Inspect reverse gear for wear or damage. Install a new gear as necessary.
19. Remove the wave washer from the reverse gear.
20. Remove the reverse gear needle bearing and the reverse gear synchronizer blocking ring.
Inspect the needle bearing for wear or damage. Install a new bearing as necessary.