Measure the distance between the upper and lower shock mounts. Jack the car up by the frame, let the wheels hang and measure the distance, add a few inches and this is the maximum length of the shock. Jack the axle on the side you are measuring and this will be the short length of the shock minus 2 inches. You don't want the car weight pulling on the shock when fully extended or bottoming out on the shock when bottomed out. G.M.