The Washer-spring,6mm is the lowest priced item on this Battery Case/electro Bracket schematic.
Parts such as the Battery Case/electro Bracket: Washer-spring,6mm, Washer,6.5x20x1.6, Case-battery, Bracket,base are included in the Kz1300a3 1981 Usa Canada Battery Case/electro Bracket parts fiche.
With four applications this Bolt-upset is the most specified part.