2017-2020 Super Duty 4WD Diesel 4" Front Dirt Logic 4.0 Reservoir Coilover - DriverDescription The Dirt Logic 4. 0 provides the ultimate in hardcore offroad dampening capacity with superior highway comfort in a big package. This massive high end shock is designed for full size vehicles that required the biggest and best Coilover shock in a bolt on configuration. Nothing else comes close. Features 4. 0" OD Stainless Steel Body 3 5 8" OD Billet Aluminum Piston 1 1 4" NitroSteel Black Piston Rod Adjustable Coilover Construction 3 4"