Parts such as the Fuel Tank: Clamp 2, Seal, Fuel Pump Comp., Cap Assy are included in the Xf50 2007 15p1 Europe 1f15p-300g1 Fuel Tank parts fiche.
In this schematic the "Bolt, With Washer" is used most often.
The Bolt, Flange(8ba) is the cheapest item from this partsfiche.