When using the middle or lower link position on the rear shocktower, there is not enough clearace between the link and the anti-roll bar holder. The basic setup position to use is the upper one, for most of the track conditions the car has been tested on, this was found to work the best as we tend to reduce the ride height of the cars.

Nevertheless, if you want to use the middle or lower position, for example when running higher ride height (on lower grip or bumpy tracks), you can use the ball joint, that is used on the steering link in the front, on the inner side of the rear link. As this ball joint is curved, it will ensure enough clearance between all the parts.

You can find this part in a tree of link ball joints: #322660