Mercury Pro Xs Lower Unit TorqueMaster 1 and Torque Master 2 lower units will bolt up and work identical. However, the Torque master 2 unit has a larger cavitation plate, so you will get more lift than the Torque Master 1 Lower Unit.

So far, the Yamaha SHO motor has been significantly better in performance and reliablity. The Pro Xs has some items that Mercury needs to fix, as Yamaha has spent 5 years fixing issues that was making the SHO blow up.

Servicing the HPDI is crucial to the life of the engine. Changing the 50000 fuel filters is a large task, but will ensure it will not lean up due to a clogged filter. Yamaha HPDI engines also had an issue with the roll pin that keeps the rings in place on the piston backing out and blowing the powerhead.

Pull the old unit off by removing the bolts/nuts that hold the lower unit in place on the mid section. Put the engine in forward gear before removal. Install water pump kit. Place the new lower unit in forward gear and place the prop on the shaft. Slide the lower unit back on the mid section lining up the shift rod and upper drive shaft. Turn the prop until the drive shaft is lined up with the crank shaft splines. Install the bolts and nuts. Fill with lower unit fluid.