I finally removed the water temp sender unit (coolant drain was an adventure in itself, looks like I killed a Ninja Turtle on my garage floor). Now I know why I was getting a slight leak from there: the threads are a different size from the intake manifold. We had a shop do some work on the Stang and last minute had them install a new sender unit. Looking at the threads of the intake manifold, they look damaged and I am at a loss of what to do. I don't want them touching my car after this (it looks like the unit was tightened down in an effort to make it work even though it's obvious it wouldn't). I was thinking of using some liquid gasket maker and apply it to the threads and screw it back in for now. The leak wasn't terrible before and that should take care of it until I rebuild the engine years from now. I know some people use an adapter, but I think the threads are beyond that now and I'm not going to tap it. Any suggestions appreciated.