On this parts fiche the Bolt (481) is the most specified component.
Parts such as the Front Brake - Caliper: 958-69527-00 Washer, Plain, Seal Kit, Disc, Brake, Bolt (481) are included in the Rx50 50special 1983 (d) Usa Front Brake - Caliper parts fiche.
The lowest price component in this Front Brake - Caliper parts-list fiche is the Bolt (481).