On this parts fiche the Grommet (12r) is the most specified component.
Parts such as the Taillight: Collar(4bh), Lens, Taillight, Taillight Unit Assy, Reflector are included in the Tdm900 2006 5psa Europe 1e5ps-351f1 Taillight parts fiche.
The Bulb is the lowest priced item on this Taillight schematic.