In this schematic the "Shoe,rr,brake (mca)" is used most often.
The most reasonably priced component used on the Xr500r 1981 (b) Usa Rear Brake Panel is the Pin Cotter 2.0mm.
Parts such as the Rear Brake Panel: Pin Cotter 2.0mm, Pin,split, 2.0, Indicator,rr.brak, Panel,rr.brake are included in the Xr500r 1981 (b) Usa Rear Brake Panel parts fiche.