These adjustable upper control arms allow for proper pinion angle adjustments at various ride heights. With a 4130 plated adjuster and jam nuts the adjustment is made easily and you don’t have to remove the arm, once the adjustments are made lock it down forever with the jam nuts. These arms come fully assembled with a spherical bearing on the frame side to allow proper rear end articulation. These arms will bolt to the stock rear end bushings or our rear spherical bearing kit. We ask that you don’t use polyurethane for the upper arm bushing on the rear end side because the polyurethane is to stiff and will limit movement.