The Suzuki GS400 1979 (N) (E01 E02 E04 E17 E18 E21 E22 E24 E25 E30 E34 E39) has eighty-four Other parts fiches.
These exploded views give you insight on which spareparts you should probably replace.
This SPECIAL MARKET (E22) fiche contains the largest amount of spare parts with forty-seven listed items