In this schematic the "Seal" is used most often.
Parts such as the Fuel Tank: Gasket, Housing Fuel Meter (nas), Cap Assy, Fuel Pipe Comp. 1, Hose (l2050) are included in the Pro 50h 1987 Fuel Tank parts fiche.
The most reasonably priced component used on the Pro 50h 1987 Fuel Tank is the Seal.