This schematic depicts all components used in the Z550g6 Gt550 1989 Europe Fg Sp Rear Hub partslist.
On this parts fiche the Brg,ball, 6303zc3 is the most specified component.
The most reasonably priced component used on the Z550g6 Gt550 1989 Europe Fg Sp Rear Hub is the Pin-cotter,4.0x35.