the original switch for the 58/59 only has 2 lugs on it (as flxible shows above), on low, one of them supplies ground, on high, both of them do (or I have that backwards, don't remember offhand). The 55-57 electric are one speed if I recall, and use a cable type switch on the dash much like the vacuum switch. It controls a switch on the wiper motor itself. 58-59 2-speed elec motor is for those 2 years only and the switch is for those 2 years only. I wanted a switch that both the knob and the bezel/nut looked original (the aftermarket ones do not). That is why I went with the one for the newer Chevy truck like I posted above. It works with the 58-59 motor, you just need to get a new nut for it and drill out your original washer/nut. Once installed, it looks like the original, the knob will cover the new nut you put on and you can either hook up washers or if you don't need them and don't want the button sticking out the middle of your knob, you can cut it off the front of the switch.
