The Bolt (3r8) is the lowest priced item on this Fuel Tank schematic.
Parts such as the Fuel Tank: O-ring, Bolt (3r8), Clip 1432435600, Bracket, Seat are included in the T50 1986 2fm England 262fm-310e1 Fuel Tank parts fiche.
Of all the components used in this assembly the Fuel Tank Comp. is the most expensive.