If you look closely at the stock t-stat you'll probably see that it's stamped 180° in one place and 190° in another (mine was).
190° is the stock temperature.
To make things worse, there's no 180° thermostat available as a direct replacement (at least not that I was able to find).
I gave the guy behind the counter my old one and told him to go through the boxes of thermostats until he found one with the same flange OD. Once he found one he checked it in the computer and it was indeed a 180° unit. The air bleed thingy was backwards, though, so I had to take it out and turn it around. I don't have the part number handy, but could check the box if need be.
Even with this mod the engine still runs over 180° according to the ODB-II readout. I can't recall exactly what the temperature was, but I think it was about 200°.