This SEAT assembly utilises four Rubb,a.seat Setti(s) - the highest specified component.
Some items from this specific schematic: Rubb,a.seat Setti, Rubber,seat Set, Holder,helmet, Washer,6x20.
The most reasonably priced component used on the Xl600r 1984 (e) Usa Seat is the Washer 3mm.