Fabtech's 6in Radius Arm system for the Ford F450 and F550 Super Duty is built to handle the on and offroad demands of the truck enthusiast. This vehicle's suspension is more robust than the Ford F250 and F350 and therefore demands specialty parts only available from Fabtech. This Radius Arm system is a complete upgrade to the factory suspension and will provide additional strength for use with oversized tires. The design has been proven in over 10 years of service in consumer, commercial and military applications. High quality components with properly designed suspension geometry is what sets this system apart from all other Radius Arm suspensions. Each Fabtech component has been designed with specific features and benefits that create this quality suspension system. Fabtech Replacement Radius Arms. Dirt Logic 4.0 Resi Coilovers. Trac Bar Relocation Bracket. Sway Bar Drop Brackets. Pitman Arm. Rear Block & U-bolt Kit. Rear Dirt Logic 2.25 shocks.