Some items from this specific schematic: Plate,headlamp Housing, Cushion, Bolt,8x16, Lock Washer.
On this parts fiche the Bolt,8x16 is the most specified component.
This Headlamp Housing - Front Fender diagram displays the required parts for the Gp100 1983 (d) United Kingdom (e02) Headlamp Housing - Front Fender.