In this schematic the "Screw, Flat Fillister(22f)" is used most often.
Parts such as the Oil Pump: Screw, Flat Fillister(22f), Gear, Pump Driven, Gasket (nas), Gasket, Pump Cover (nas) are included in the T80 1986 2fl England 262fl-310e1 Oil Pump parts fiche.
The component with the lowest price in the OIL PUMP schematic is the Plug, Straight Screw (22f).