I知 building a 1967 CS Holiday Coupe as a restomod, I致e upgraded suspension, converted to power front disc brakes, added vintage air AC, rewired everything, replumbed fuel and brakes, added electric windows and keyless door locks. I知 trying to wire up dual electric fans on an aluminum 3 row radiator and I知 wondering if anyone has heard of or seen a sending unit that can perform like a thermal switch to turn on the fans as well as provide a signal for a water temp gauge. I only have 1 hole in my original intake manifold on this 1967 330 High Compression motor.

Thanks!

 

I just got a Derale fan controller that uses a push-in probe that goes into the radiator core, as my 62 F85 has the same problem.

 

I bought the Davies Craig 0444 with the push in rad probe, so far so good. It has very good reviews, dual 40 amp relays and two 30 amp fuses. Almost every fan controller, including two Derale failed almost immediately, one had a defective probe out of box and one had wiring that 3rd world children must have assembled.

 

You would have to use the existing sender, tap the line, and make your own fan controller (assuming it's a gauge and not an idiot light). That's what I did for mine, but I have many other complications.
The typical aftermarket fan controller uses the radiator probes like the guys said. Those work just fine, you just have to put the probe where they tell you to, and spend a bit of time fiddling with the settings. Don't get wound up with whatever temperature numbers are on the dials - just adjust it to where it keeps the engine where you want it.