I was driving my Challenger last night and it started heating up suddenly while stopped at a railroad track. I pulled over and let it cool down. The upper and lower radiator hoses were both hot, there was seepage around the heater hoses on the fender, the puke tank was full and overflowed a pint or two and the fan would spin about two rotations when spun by hand.

When I left I got on roads that would let the air flow through the radiator while driving at about 45 MPH and it stayed in the lower operating range. I just drove it last week in daytime temps of 95 degrees with a bunch of stops with no problems. Am I on the right track with the fan clutch?

Yes I think you are on the right road. 2 revolutions is too many hot or even cold.

They can go bad at anytime, sometimes gradually or all at once like it sounds like yours did.
I bet you can not hear the fan anymore when reving it up.

I've had 2 or 3 of them go bad on me over the years. They were all hi mileage originals, the one on my 340 is about 12 years old now and still cools my car in 110 degree temps. I've been tuning on it lately and still notice alot of fan sound when I rev it up, you should hear the fan even when it's cool.

just as cheap insurance, when you replace the clutch replace the wp too.

I have only had one go bad, and I replaced it, shortly the wp died and took out my radiatior.

yeah, they say your supposed to store them flat, but that doesnt help when it is installed....Maybe the Thermo-trol ones with the spring in them are better/longer lasting?