Sump drain plug and washer for Nortons singles and twins 1948 on. Models 7, 1 ,16H, ES2, 18; chaincase drain plug later featherbed twins; oil tank drain plug twins 1955+; gearbox level plug. Thread is 28tpi BSP NOT BSCY AND NOT UNF Original part number: 13765 - crankcase drain plug; (Post 1948 with plug under sump) x 1 13881- drain plug washer (washer changed in 1957 but this one will still fit) x 1 13833 - drain plug washer x 0
