1949 and 1950 at Shipley and 1954 onwards at Brum. The Lucas MC45 dynamo was replaced by the slimmer Miller alternator after two or three years. I’m not sure of the year. HOWEVER…. In typical Scott fashion, Shipley did a “Modernise your Scott” leaflet, and sold the MC45 dynamo, and distributor set-up, to owners of earlier magdyno equipped machines. In the same way they offered Dowty forks to replace girder forks, full width hubs, etc..