Parts such as the E-18 Lower Crankcase: Clamper Cable, Crankcase Under, Bolt Drain, Oil Seal 12x25x45 are included in the Cb450k3 U.s.a E-18 Lower Crankcase parts fiche.
On this parts fiche the Washer,plain, 6mm is the most specified component.
The most expensive part in this assembly is the Crankcase Under.