On this parts fiche the Bolt-upset-ws,10x16 is the most specified component.
The Washer-spring,18mm is the lowest priced item on this Rear Hubs/brakes schematic.
A sample from the products for the Rear Hubs/brakes include: Washer-spring,18mm, Shoe-brake (nas), Spring,shoe Clamp, Panel-assy-brake,rr,l.