Some items from this specific schematic: Screw Washer, Tan*g125mu/type1*, O-ring, Clamp D 12.0 Tube.
The lowest price component in this Fuel Tank parts-list fiche is the Washer,plain,12mm.
twenty-three components are shown in this Gb500 Touristtrophy 1990 (l) Usa California Fuel Tank exploded diagram.