On this parts fiche the Screw,cross 4x6 is the most specified component.
A sample from the products for the Fuel Tank include: Washer, 8.3m/m, Cushion,fuel Tank, Clip B10,tube, Screw-washer,5x6.
The component with the lowest price in the FUEL TANK schematic is the Screw,cross 4x6.