04-06-2020, 07:45 AM
Good point about the SP numbers. Supersports bits were SP and I think maybe some later GE castings too (e.g. the front timing chest castings for the Brooklands - the one with the tacho take-off). 9B & 9C were obviously later, following on from SP, and applied to works TT components then production sports bits. S was usually stamped on the gearbox for EA 'Usters' and Nippies but as far as I know rear axles have no specific markings to denote Sports (someone might correct me on that).