With a quantity of four pieces, the O Ring,16mm is the most used part in the CRANKCASE diagram.
Some items from this specific schematic: Gasket,12.5x18x1.5 (nas), Bolt-flanged-small, Plug,main Gallary,18x, Pin,dowel,6x16.
The lowest price component in this Crankcase parts-list fiche is the Washer-plain-small,6m.