The Stovebolt Site Forums The Shop Area Engine Shop Temperature Sensing Bulb and Oil pressure Line

I am trying to figure out where the thermostat temperature sensing bulb goes on a 235. I have a spot on top of the head which I thought was correct but I also have the same size thread just below the carb on the exhaust manifold which I have no idea what that is for. Both threads however are just slightly loose for the thread on the thermostat sensor. So first off where should this go and secondly when switching to the 235 from 216 does it require a different size plug with a smaller thread? Lastly, what is the hole for that's under the carb?

As far as the pressure sensor line, I see one end is slightly longer than the other. Which end goes which?

Pics included.

Thanks for the help!