Ducati Diavel Workshop Manual page 758

Gearbox assembly: gearbox shafts
Once removed, it is possible to replace the special rollers (13).
Remove gear selector forks (29) and (28).
Remove the gearbox primary (2) and secondary (25) shafts complete with gears, taking care to recover the spacers on
the ends of the shafts.
If the bearing inner rings (A) are left on the shafts, slide them off the ends of the gearbox primary (2) and secondary (25)
shafts (Sect. 9 - 9.2, Separation of the crankcase halves).