GearWrench 3473 1/2” Drive Diesel Fan Clutch Wrench The GearWrench 3473 1/2” Drive Diesel Fan Clutch Wrench can be used in conjunction with the 3900 GearWrench Universal Pulley Holder to remove and replace the thermostatic fan assembly on Ford 6.9L, 7.3L, and & 7.3L Diesel engines. The GearWrench 3473 1/2” Drive Diesel Fan Clutch Wrench can be used with 1/2” drive tools and a torque wrench, refer to factory service manual for torque specifications and thread direction, and wrench opening is 48mm (1.899”).