Parts such as the Front Calipers: Guide,pad, Axle No.1, Bolt,caliper Housing, Axle No.2 are included in the Gs1000g 1981 (x) Usa (e03) Front Calipers parts fiche.
The most reasonably priced component used on the Gs1000g 1981 (x) Usa (e03) Front Calipers is the Bolt(10x37).
On this parts fiche the Guide,pad is the most specified component.