The Nut,flanged,6mm is the cheapest item from this partsfiche.
In this schematic the "Collar-battery Case" is used most often.
A sample from the products for the Taillight(s) include: Damper,tail Lamp, Washer,6.5x20x1.6, Nut,flanged,6mm, Collar,6.1x8x15.7.