24. After I have everything hooked up and I'm ready to test the motor and transmissions, I mark both the transmissions with a black marker to simulate an arm. Then when I turn the motor on, I can check and make sure that both the transmissions are turning the way they are supposed to and also when they have parked properly. When I'm sure everything works right, I then install the wiper arms and blades. Doing it in this manner assures you get the arms and blades in the correct position the first time (and you don't scratch up the paint on the cowl panel).