On this parts fiche the Roller,4x13.8 is the most specified component.
The Screw Flat 6x16 is the lowest priced item on this E-15 Gearshift Drum schematic.
Some items from this specific schematic: Washer, 6x2.3, Washer, Drum Stop, Drum, Gearshift, Arm Comp,drumstop.