UMI Performance 67-70 GM B-Body Adjustable Upper Control/Trailing ArmUMI Performance offers an on car adjustable control arm for the rear of the GM B Body vehicle. This rear upper control arm for the 65 66 GM B Body is a direct replacement for the factory arms and is designed to minimize wheel hop, improve corning, and help track consistency. It allows for easy pinion angle adjustments without the need to remove it from the vehicle. The control arm features greaseable bushings, TIG welded construction, and a 4140 heat