HelloCustomermy name is Mark.
The thermal viscous fan drive/fan blade assembly is attached (threaded) to water pump hub shaft Fan Blade/Viscous Fan Drive - Gas Engines - Typical Remove fan blade/viscous fan drive assembly from water pump by turning mounting nut counterclockwise as viewed from front. Threads on viscous fan drive are RIGHT-HAND. A Snap-On 36 MM Fan Wrench (number SP346 from Snap-On Cummins Diesel Tool Set number 2017DSP) can be used. Place a bar or screwdriver between water pump pulley bolts Fan Blade/Viscous Fan Drive - Gas Engines - Typical to prevent pulley from rotating.