Little update on this. It is definitely the upper part (thermo housing) that is leaking. I can feel it at the seem and even see the coolant pooling in the top of the housing. It seems to be leaking at that seam and just collecting down by that short bit of hose.

Well, it could be leaking elsewhere as well, but if I am tracing it top down, the thermo housing is definitely the first place. It is wet all the way around the seam - top and bottom.

Before I take this apart, what am I getting into here?

If it is leaking around the seam, is that just likely a seal in there, or is there other things that could cause the same type of leak? I haven't ever been inside the thermostat housing.

Any suggestions on what parts I will need to/want to replace while I have it out and opened up?

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