Well it has one, here is the thermostat housing to head gasket.
For practically all vehicles, just follow the upper radiator hose and it should lead you right to it, but Ford's could be different.
rockauto.com only lists a Motorcraft thermostat, for 29 bucks, I never was one to save a couple of bucks on a thermostat, could pay dearly if it stays closed. Temperature is not even listed, but can bet its at least 195. On the newest vehicles, 220 is getting common.
It is very slow to heat up, the temp gauge is showing in the middle but the radiator shop that flushed the heater core said on their scanner it isn't really running that hot. I bought it last winter and it worked fine, it has about 130,000 miles on it. Far as I can tell all the heater controls look to be working OK, by actually watching everything function by dropping the glove box door.
I am forced to remove the thermostat housing when doing a flush job. Since the block drain blocks are no longer accessible, use a leaf blower at that thermostat opening and pray I can blow out most of the water so I can hit my 60-40 mix I need in my neck of the woods.
Ironically, your shop just flushed out the heater core, sounds like a shot in the dark, with scale buildup, entire system should be flushed. Is possible your thermostat is not fully closing that causes your cooling system a longer time to heat up. Only takes just a small crack.
New thermostat and water pump seems to have cured the problem, not those thermostats are a real pain to change even with a garage lift. It is running 198 degress now on the scanner, I guess you can't really count on the dash gauge for accurate temp readings. fixed