[markjohnson]

They do work well but require removal of the upper control arm bushings and drilling into the lower ribs of your rearend housing. You know how a stock Chevelle or GTO squats in the rear on a hard launch and the body drops down over the rear axle? Well, these change the imaginary intersection point of the control arms and make the rear axle plant into the ground while the body of the car raises up. Genuine Suspension was the popular manufacturer of these.