A sample from the products for the Crankcase Cover 1 include: O-ring (6g8), Clamp, Bolt, Flange(4bh), Cover, Crankcase 2.
The O-ring (2h9) is the lowest priced item on this Crankcase Cover 1 schematic.
In this schematic the "Bolt, Flange(4kg)" is used most often.