On this parts fiche the Nut,flange,6mm is the most specified component.
The Cx500c Custom 1980 (a) Australia Seat consists of eight pieces with the Seat Comp.,double being the most expensive.
Parts such as the Seat: Plat,seat Set, Seat Comp.,double, Stay,fr.seat, Bolt,flange,8x14 are included in the Cx500c Custom 1980 (a) Australia Seat parts fiche.