electrical fan switch - is a selonoid OK?
 

I have a 5.8 that was not staying coolw/the stock set up so I replaced it w/a Taurus fan using the parts in this link:
http://www.fordmuscle.com/archives/2...an/index.shtml

Worked good for a while then coolant spilled on the relay. I got another one and it quit too. A buddy replaced it with a regular Ford starter selonoid and now it works. On the down side, I hear the selonoid click under the hood as the fan comes on and then everything (lights) will dim and the volts drop down to just above 13. Is this OK?

I'd get another relay, and relocate it so it doesn't get damaged. A solenoid has a higher draw on your electrical system than a relay would. Besides, that solenoid isn't designed to be "on" for more than a few seconds at a time. If you continue to use it, the internal contacts will start to weld themselves together, and the fan will be stuck on all the time.