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So is it just the switch that makes the multiple speeds? or do you need a motor to match the switch also?



Good question.

On the two-speed motor assembly there is a resistor block (looks like a balast resistor) that slows the motor down. The dash switch sends power through the resistor on low speed or direct to the the motor on high.

On the three-speed motor the speed is controlled by the windings on the motor and the switch sends power directly to the appropriate winding for the selected speed.

To convert to three-speed you need the following:
3-speed motor
3-speed switch
3 speed wiper link/arm and bushing

"I think" you need to add a connector to the harness since the 2-speed has terminals on the motor and the 3-speed motor has a harness.