-SG- The Four Speed 'cross-over' box was fitted to various production Norton models from '26 -'30. It was first used in the sidecar TT events and then - with kickstart mechanism fitted - on models 14, 24, 34 and 44. Somewhat surprisingly, a Model 24 from 1926 has surfaced in South Africa although a previous owner (possibly in what is now Zimbabwe) has discarded the four speed box and fitted a Sturmey Archer three speed CS type, by the simple expedient of turning the rear wheel round so that the drive sprocket is on the left. The new owner has not yet decided whether to search for a four speed box ... time will tell! Meanwhile here are scans from my files of the relevant parts list / maintenance instructions for this box - not sure of the date of publication but probably late twenties.