One side of the Panhard rod attaches to the rearend while the other is joined at the frame. The stock Panhard rod is generally light duty and tends to deflect when the car is driven hard. Raising or lowering the ride height shifts the rearend laterally (no longer in the center of the car) and causes the rearend to be unstable around turns and over bumps, depending on the final angle of the Panhard rod (not parallel to the ground). When the car originally went together, the builder cut the stock rod, threaded either end, and machined a knurled adjuster from aluminum stock. While this is good for centering the axle, optimally the bar should be level with the ground. As you can see here, it isn’t.