[65comet]

I had heard about that one being so hard, so when I had to replace the radiator I put in a new sensor at the same time.
On another note, regularly check your coolant reservior to see if tranny fluid is floating on top. The factory radiators like to crack internally swapping fluids. It doesn't take long for antifreeze to seize up a transmission as I found out. My wife was the daily driver at the time and she thinks she just has to put gas in and everything else takes care of itself. So maybe you'll have to get two with one stone and with an easier access to that sensor. Though it sucks to pay for the radiator, it sucks worse to also pay for a transmission.