In this schematic the "Nut, Spring" is used most often.
The Nut is the lowest priced item on this Taillight schematic.
Parts such as the Taillight: Nut, Spring, Nut, 01416 10w 12v, Bulb 12v 5w are included in the Vp300 2004 1s61 France 1c1s6-300f3 Taillight parts fiche.