On this parts fiche the Nut,flange,6mm is the most specified component.
Some items from this specific schematic: Rr.fender Ext., Wash,chain/c Set., Bolt,flange,sh 6x18, Rubber,pivot Unde.
The Rr.fender Ext. is made up of components including this Rr.fender Ext. which is the most expensive.