Average used black rear swing arm to suit K75; K100 8v series. Bearing feel smooth but are not guaranteed but a good option would be to replace them before fitting to save work at a later date if you have a mind too.
Swing arm will need a good clean as well.
The rubber boot looks like it has no splits but you may want to change it for a new one. Comes with the wire clip ring.
Came off a 1997 K100RS that sat for twenty years and had 65,000 ks on th clock.
After cleaning the injectors, the motor ran really nice.