Parts such as the Lower Crankcase: Bolt,flange, 6x32, Case,oil Filter, Bolt,flange,6x40, Seat,oil Spring are included in the Cb400nc 1983 (d) Australia Lower Crankcase parts fiche.
The most reasonably priced component used on the Cb400nc 1983 (d) Australia Lower Crankcase is the Washer,plug Drain 14.
This LOWER CRANKCASE assembly utilises four Bolt,flange, 6x32(s) - the highest specified component.