On this parts fiche the Bolt-upset-ws is the most specified component.
The most reasonably priced component used on the Klf400-b6 Bayou4004x4 1998 Usa California Canada Headlight(s) is the Bolt-upset-wp.
A sample from the products for the Headlight(s) include: Bolt-upset-wp, Rim-lamp, Lens-comp,head Lamp, Collar,l=13.1.