This 4 Inch Lift for the 2017 to 2021 Ford Super Duty F-250 | F-350 4WD features Superlift’s massive, high clearance, precision engineered, tubular radius arms design to bolt right into the factory mounts giving your ride a truly custom look and an easy install . These heavy-duty Radius Arms utilize a press-fit Cleveite® rubber busing for superior vibration dampening and durability. This 4 Inch lift kit also contains new, diesel engine specific rated coil springs. A new track bar relocation bracket that ensures proper steering geometry and track bar phasing.