I run a Taurus 2-speed fan, I run it on low through a switch rated for enough amps to handle low speed. I've got everything I need to wire up both speeds through relays using a thermo switch to activate each speed, just need to get it hooked up.
You can get the fan from almost any 3.8L Taurus, Mercury, or Lincoln. Crown Vic uses a mech. fan so don't bother looking there. Don't get the 3.0L fan.