Parts such as the F-18 Fuel Tank - Seat: Cap Comp.,filler, Stay, B, Strainer, Stay, A. Strainer, Spring are included in the Gl1000ltd U.s.a F-18 Fuel Tank - Seat parts fiche.
This schematic depicts all components used in the Gl1000ltd U.s.a F-18 Fuel Tank - Seat partslist.
The Screw,cross 3x6 is the cheapest item from this partsfiche.