The picture in the AM catalogue is indeed titled "thermostat housing" but in fact shows the coolant outlet manifold. Obviously those guys don't know what they are talking about. When you remove the part you will clearly see that there is no thermostat inside.

 

The thermostat is on the bottom of the engine under the alternator. Pain in the butt to get to and not a recommended DIY project unless you have a good 6 hours. My buddy is a trained mechanic with his bachelors in automotive engineering and it still took him 5 1/2 hours from start to finish. The part we are referring to, the black manifold to the left of your intake manifold is -not- the thermostat housing, it is labeled wrong. But it is the correct part. But before you go and buy a new part, check to make sure that your hoses are on correctly, the clamps are on correctly, and the bleeder valve is shut and sealed properly. Doing that may save you some money.
I would also check to make sure that all of your hoses aren't leaking. Sebring thermostats can get gook and dirt in them causing them to stay -open- or stay -closed- which may cause your engine to run hot and overheat, or run low and your fans won't come on at the right times.
Check the thermostat, because if one part goes out, the other is soon to follow.

 

Cool, thanks to all for the advice and information. In my particalar case, it's the Coolant Outlet that has a leak, so I can focus on that without any confusion. There is no overheating or thermostat related issues, so the clarifications really do clear the picture. Now I can proceed with a proper diagnosis and repair.