The Pin 20x20 is the lowest priced item on this Rear Swinging Arm schematic.
The thirty Gs500eu 1990 (l) Germany (e22) Rear Swinging Arm component parts are all listed in this schematic.
A sample from the products for the Rear Swinging Arm include: Bearing(22x29x30), Nut, Washer (10x18x3.2), Bearing(17x24x25).