Parts such as the Headlight: Washer,plain 12mm, Holder,l,coupler, Screw,cross,5x16, Bulb, Headlight are included in the Cb400nd 1984 (e) Germany / Full Power Type 1 Headlight parts fiche.
On this parts fiche the Nut,unit Holder is the most specified component.
Of all the components that make up this Headlight the Screw Pan 5x8 has the lowest price.