Water temp snding unit replacement

[GUITAR1989]

Hows it going guys   I bought a spiffy looking autometer traditional chrome water temp gauge and im gonna replace the old sending unit with the autometer one. I was wondering if anybody could fill me in on what the steps would be to replace my water temp sending unit. Im just tring to be cautious and get all the input I can before I go pulling the old sender out. One of my main concerns is the coolant getting all over. Should I drain the coolant out before I take the old sender out? oh yeah its in a 74 350 if that matters.
 Thanks for your time guys

[HIGHPLAINSDRIFTER]

I didn't drain mine before I changed my sending unit.  When I pulled it out there was some coolant that leaked out, but I think it was just the coolant left in the block because it was not very much.  After I changed the unit I filled it back up, ran it for a few minutes, and then added a little more.  This was probably not the right way to do it, but it worked for me and the burns  I got from the "hot coolant" have healed nicely.

[Captkaos]

I wouldn't change it when it was hot, but if it is the factory location, I would drain the coolant down some.  If not you are going to do it at the radiator, you will end up doing it from the head and get it everywhere.

[GUITAR1989]

I had a fealing it would be messy if I didnt drain it out first. Just wanted to ask u guys to make sure it was necessary. I really appreciate the help