03 Mounting the upper links to the differential is done by this supplied bracket. With a triangulated four-link, the upper two links (control arms) are closer together at the differential, and farther apart at the front crossmember. The upper links keep the axle from rotating, and keep the pinion angle constant. The "triangulated" upper bars also keep the rear end centered under the car so a Panhard rod is not needed. One downside to a triangulated system is called roll bind. This is where there is a lateral-corning force that is applied to the rear end, and basically binds the action of the suspension movement. This can, however, be controlled by using strong, high-quality heim joints or urethane bushings--which is what Heidts uses--that have much less deflection than rubber bushings.