Some items from this specific schematic: Screw,tapping,5x12, Bolt,hex.,6x20, Reflector,reflex, Screw,tap.,4x12.
On this parts fiche the Collar,t.mounting is the most specified component.
The most reasonably priced component used on the Pk50 Wallaroo 1999 (x) Belgium / Mp Std Rear Fender is the Bolt,hex.,6x20.