Control Arm - Adjustable. Pedders control arm assembly units are manufactured to exacting dimensions and quality equalling or exceeding Original Equipment Manufacturer(O.E.M) specifications. Rear Adjustable Upper Trailing Arm. Helps to correct pinion angle of diff when lifting suspension. Arm is bent to accomodate for long range fuel tank installation. Sold Seperately. Control arms are an important structural part of the vehicle’s front suspension, attaching the wheel hub and steering knuckle assembly to the vehicle’s frame. Many vehicles can go through their entire life without ever having a control arm replaced. However, some situations necessitate the control arm’s replacement. A few examples of this are: Vehicle Accident Vehicle is in a accident, resulting in damaged and bent control arms. Worn Ball Joint Ball joint (if applicable) may be permanently pressed into control arm, making it impossible to replace the ball joint without replacing the control arm. Worn Bushings Bushings where the control arm is attached to the frame are necessary to allow the wheel to move up and down as it travels across bumps and dips in the road.