On this parts fiche the Gasket,6x12x1.13 (nas) is the most specified component.
A sample from the products for the Oil Pump include: Screw-pan-cros, Oil Seal-oil Pump Sht, Key-woodruff, Ring-o,cap,camshaft S.
The component with the lowest price in the OIL PUMP schematic is the Screw-pan-cros.