You could always just copy the wiring and use the resistor diode pack for a 95-99 Ford Contour 2.5 V6 and the dakota digital control to make 2-speed fans.

I have the whole Contour fan setup on my car with the dakota digital controller, they are very quiet and it runs both fans at low speed when cooling is needed, switches to high when it hits the preset point. Or you could have a switch and use a cheap controller for the slow speed.

PWM is nice but can get spendy, and I'm not sure how reliable the controllers are.