Ok, so everything is back together and seems to be running fine. I did notice a squeel after first starting it when cold the first few times, but it seems to have gone away. I also hear a little more noise than it seemed I had before, but I didn't drive the car enough before to really gauge this. It sounds like the SC coupler to me, but it is just a slight noise. How crucial is this to change?

My temp gauge is also acting a little more normal. I didn't see anything wrong with the old thermostat, but I assume it was opening too early maybe.

I do have another question too, and since I noticed it while putting everything back together after the LIM operation I hope it is OK to ask it here. There is a big hole in the engine block right under the thermostat housing and temp sensor (probably the size of a nickel). What is this hole for?