Ford 2003 Mustang Workshop Manual page 2837

40. Install the fifth gear shift fork, the synchronizer assembly, the synchronizer cone and fifth gear
as an assembly.
41. Install a new split pin.
Install the pin until it is flush with the fork.
42. Install a new snap ring.
43. Install the third/fourth shift finger, then install a new split pin.
Install the split pin until it is flush with the shift finger.