On this parts fiche the Nut,flange,6mm is the most specified component.
The component with the lowest price in the FUEL TANK schematic is the Nut,flange,6mm.
A sample from the products for the Fuel Tank include: Bolt,flang,6x16, Cap Comp,fuel Fil, Collar,6.2x12, Rub,hd/lt Brkt.