Use a flat screwdriver to pry the stock upper rubber isolator from the upper strut mount assembly, which will be used with the caster/camber plates. There are two styles of struts used on S197 Mustangs-a twin-tube and an inverted mono-tube. Install the spacers as shown based on the type of strut your car has and whether it's lowered or not. Spacer stack installation is clearly spelled out in MM's thorough instructions and varies due to strut style and ride height. Shown here is a short spacer.