Some items from this specific schematic: Washer (10.5x30x2.3), Cover,stay, Bulb(12v23w,stanley,a4577a), Spacer.
On this parts fiche the Screw is the most specified component.
The most reasonably priced component used on the Gs450l 1982 (z) Usa (e03) Turn Signal Lamp is the Screw.