The Washer,plug,drain 12 is the lowest priced item on this Gasket Kit B schematic.
On this parts fiche the Gskt Con Cap is the most specified component.
Some items from this specific schematic: O-ring,14.7x3.7, Pkg Oil Strainer (nas), O-ring,8.4x2.4, O-ring,14.8x2.2.