Some items from this specific schematic: Dust Seal,steering Upr, Washer, Nut, Bolt.
The Steering Stem assembly is constructed from several parts from which the Stem,steering is the most expensive.
The most reasonably priced component used on the Gs400 1979 (n) (e01 E02 E04 E17 E18 E21 E22 E24 E25 E30 E34 E39) Steering Stem is the Ball.