Parts such as the Seat: Cable,seat Lock, Cowl Set, Rr. (wl) *, Set *type3 1*, Rail,rr,g*nh146m* are included in the Cb500 1998 (w) Austria Seat parts fiche.
In this schematic the "Nut,flange,6mm" is used most often.
The Washer,plain,5mm is the cheapest item from this partsfiche.