Some items from this specific schematic: Diaphragm, Screw, Cylinder Assy,rr Master, Pin.
The most reasonably priced component used on the Gsf1200s 1999 (x) (e02 E04 E17 E18 E22 E24 E25 E34) Rear Master Cylinder (gsf1200sav/saw/sax) is the Pin.
On this parts fiche the Nut is the most specified component.