Parts such as the Rear Caliper (model K/l/m/n): Shim,pad, Spring, Bleeder, Boot are included in the Gsx600f Katana 1989 (k) Usa (e03) Rear Caliper (model K/l/m/n) parts fiche.
Check out any of the nineteen Rear Caliper (model K/l/m/n) components enlisted.
On this parts fiche the Seal,piston is the most specified component.