Parts such as the Taillight: Connector,harness, Bolt,hex 5x25, Reflex Refrector, Cub Cord Tailligt are included in the Xl600r 1984 (e) Usa Taillight parts fiche.
The Bolt,hex 5x25 is the cheapest item from this partsfiche.
In this schematic the "Collar,taillight" is used most often.