As fitted to Lucas E3LM Dynamos. These are new armature (not Re-wound) and no exchange units are required. 179mm Parallel shaft with thread at drive end. Fits Ariel singles (1954-58) , BSA B&M Group (1950-57), Douglas 80 and 90 (1950-55), Royal Enfield singles (1951-55), Royal Enfield Twins (1954-55), and Norton singles (1950-58). 6V, 60W.