On this parts fiche the Washer(6a1) is the most specified component.
The most expensive part in this assembly is the Rear Fender Comp.
Parts such as the Fender: Grommet 839774310000, Grommet 152845180000, Damper, Rear, Nut 168216350000 are included in the Rd350 1973 Usa Fender parts fiche.