There are 5 different gearboxes used on the pre-unit A, B and M group machines and 4 different gearboxes for the pre-unit ‘C’ group. There are however similarities between them and for this listing the gearboxes have been grouped as follows:-
- Pre-war models except M and C group
- 1938-48 M; 1946-48 B; 1949-63 M and B Plunger
- 1946-57 Plunger A; 1954-63 S’arm A and B; C10/11/11G 4 speed; C10L/12 4 speed.
- C group 3 speed.
- Unit models.