The lowest price component in this Taillight (km100-a1-a4) parts-list fiche is the Washer-spring,6mm.
This schematic depicts all components used in the Km100-a3 1978 Usa Canada / Mph Kph Taillight (km100-a1-a4) partslist.
The Taillight (km100-a1-a4) is made up of components including this Tail Lamp Assembly,black which is the most expensive.