4. The rear shocks are essentially a bolt-on, bolt-off affair. The larger RS 9000XL shocks feature a 2.75-inch body, an 18mm chrome-plated piston rod, and Rancho's patented red polyurethane bushings. We like the fact that when you twist the nine-position knob, you can actually feel a difference. When towing we run them stiffer to help reduce trailer sway.