The most reasonably priced component used on the Sp600 1985 (f) Usa (e03) Rear Cushion Lever is the Nut 12mm.
The fourteen Sp600 1985 (f) Usa (e03) Rear Cushion Lever component parts are all listed in this schematic.
This REAR CUSHION LEVER assembly utilises six Washer(s) - the highest specified component.