I have been using a piece of firewood between a blade of the propeller and the hull to prevent the shaft from turning when cranking the gear puller with a wrench. If I were to use an impact wrench on the gear puller nut, I would leave the firewood in place. I would think that would absorb the torque of the impact wrench, although I can see how some vibration would get to the transmission. Am I thinking correctly about this?