These 5 lift rear leaf springs for the 2017 - 2024 Ford F - 250F - 350 Super Duty are progressively rated to improve the ride quality of your Ford Super Duty pickup, as well as increased performance. The multi - leaf construction ensures a smooth ride with less chance of spring fatigue under load, minimizing sagging. The bottom leaves of the pack are flat to provide a secondary overload rate preventing harsh bottom outs and smooth transition through the suspension travel. ICON 2.0 Aluminum Series or 2.5 Aluminum Series Vehicle Specific tuned shocks recommended for best ride quality and performance on - or off - road.