The lowest price component in this Water Pump parts-list fiche is the Bolt,flange,6x25.
In this schematic the "Dowel,pin,8x14" is used most often.
Parts such as the Water Pump: Oil Seal,12x28x7, Cover,water Pump, Bolt,flange 6x45, Bolt,flange,6x25 are included in the Xl600v Transalp 1988 (j) Switzerland Water Pump parts fiche.