Parts such as the Seat: Lever,l.seat Lock, Washer,seat Lock, Rubber,seat Mount, Bolt,seat Lock are included in the Cx500 1980 (a) General Export / Mph Seat parts fiche.
In this schematic the "Nut,flange,6mm" is used most often.
The Seat is made up of components including this Seat Comp,double which is the most expensive.