Standard Motor Products makes these four position heater blower motor switches which look period correct on our trucks:
HS-98
They also make an infinitely variable rheostat switch for both 6v and 12v systems. I like it on my heater because it lights up when you turn it on.
HS572 (12v)
HS-92 (6v)
www.ecatalog.smpcorp.comI have the original 3-way switch (assume low speed, off, and high speed). I am wanting to wire up so that power is on only when ignition switch is on. I will be splurging on an original look AM/FM stereo that I want to wire the same. Did you wire up so heater fan shuts down with iginition switch off? If so, how did you wire it?