The last thing to do is put in a temperature switch to turn the fan on and off. there is a black wire from the relay that goes to the temp switch (it looks like a temp sensor, but it actually a switch that activates at specific temperatures).
I was going to put it down on the passenger side head where the sensor for the guage goes on the driver side. But i was unable to get the plug out. So i got a thermostat housing off a 70s model 350. It had a threaded hole just the right size, well kinda. The hole is 1/2" pipe thread and the switch is 3/8" pipe thread, so I had to use the supplied reducer.
Well the housing worked great for the temp switch but caused lots of problems with the upper radiator hose. I had to cut it in 2 places, rotate 1 end, cut a piece out of another hose and slice it together with some 1 1/4" tubing. here's the pic.
