The Yamaha REAR ARM has twenty products enlisted in the schematic.
On this parts fiche the Collar(4dp) is the most specified component.
Parts such as the Rear Arm: Bearing(4dp), Bolt(3fv), Hook, Nut, Self-locking(38v) are included in the Tz125 1998 4jt5 Italy 284jt-100e1b Rear Arm parts fiche.