On this parts fiche the Cap,pipe Co-rider Grip is the most specified component.
Some items from this specific schematic: Emblem, Cushion,tool Back, Bolt, Front, Nut.
The most reasonably priced component used on the Vs1400glf 1991 (m) (e01 E04 E17 E21 E22 E34 E39) Pillion Rider Handle (model S) is the Bolt.