Well, if it is the complete kit it is a real bargain for $100 because they used to sell for $250.

You do not need any u-joints, as the steerable outdrive comes with all the parts. The motor uses a coupler that attaches driectly to the prop shaft. All you need to do is install a motor of your choice and an esc. I would, however, install the stock motor and run it a few times to give yourself a basic performance level to judge the model by. Then later any improvements you make will be measureable from there.

I found that the stock battery location as indicated by Kyosho made the CG too far aft and the boat could not get up on plane. Placing the battery forward of the gearbox solves the CG problem. The strut is adjustable and you will need to experiment with different positions all dependent on your motor and prop you are using.

Using a hot car motor, direct drive in a large boat like this, is normally a recipe for a melted motor. But since you have the gearbox, the motor will be under less strain. However, you may still need to use smaller props to allow the motor to run without overheating. Be sure to hook up the water cooling coil to the new motor.