Ford 2003 Mustang Workshop Manual page 2793

41. Remove the reverse idler gear assembly.
42. Remove the reverse idler gear from the shaft.
Inspect the gear for wear or damage. Install a new gear as necessary.
43. Remove the reverse idler gear bearing.
The reverse idler gear is three separate pieces: bearing, spacer, bearing.
Inspect the bearing for wear or damage. Install new bearings as necessary.
44. Disassemble the clutch housing.
1. Remove the countershaft bearing cup and shim.
2. Remove the input shaft bearing cup and shim.
3. Remove the input shaft seal.
Carefully pry out from the inside of the case.