Pivot ball height is critical during assembly. The factory ball supplied by Ford Performance is the long silver pivot ball. This pivot in most cases is too long, which then locates the fork already in contact with the pressure plate fingers to the throw out bearing. The fork is then too far rearward. The Shorter black ball can be used to remedy this issue, and if you are unsure what exactly you need, the adjustable ball allows you to fine tune the height yourself.