Two wrenches are needed to perform removal and replacement of the viscous fan clutch. One wrench to hold the water pump stationary (depending on the application a 99800A, 61600, 61500B, 10800 or 10900 ) and the other wrench a 95210 to remove and replace the viscous fan clutch. The 95210 works with most gas and diesel viscous fan clutches, with either a 36 mm or 48 mm hex holding the viscous fan clutch to the water pump.