What's the hole in the intake for....collecting antifreeze

I had the same thing happen to me after changing the thermostat in my car. I made sure I when I reassembled it I put a nice fine bead of water pump RTV both sides of the gasket but I still got a leak. I took it back apart and checked my housing and low and behold the ears were bent down slightly causing the bottom of the housing to not be flat. A few seconds on a belt sander and all was back to flat. I did do one other thing as well as it was a pain to clean up all of the rtv and even the good thermostat housing gaskets are just thick paper gasket material and seem to be hit or miss if they seal. I spent some money and bought a silicone gasket from Real Gaskets. No more rtv mess to clean up when changing a thermostat and a lot less clamping force needed to make a good seal so no more bending of the ears on the housing, plus it is reusable. I have not had a leak since installing it. So if you have the time to wait to have one shipped I highly recommend the Real Gaskets silicone gaskets. The part number for the mopar V8 thermostat housing is RG-53063, they are 9 bucks plus shipping and worth every penny.