Be aware that the t stat can get "tired" and not open all the way anymore. I boiled my old one with my new motorcraft and they would open about the same time but the old one only opened half as far. This was adequate for empty driving but would it would over heat with a load.
If you have any doubts, I would just replace it with an OEM unit. They aren’t all that expensive, and probably one of the most important gizmos on these engines. An aftermarket t-stat will not flow enough to properly cool these engines FYI.
That's what I've read, and it's why I am eager to replace it. I have 45 miles minimum to drive to get the new Motorcraft thermostat. I couldn't get Walmart or Amazon to ship one to a PO Box for some stupid reason.
The next is a town about 10 miles away along the way so if I don't like what the real temp gauge is showing by then, I could always stop and remove the thermostat entirely (after it cools down again, after however many hours it takes) until I can get another 35 miles down the road to get the new one.
I will be on a back highway where I can stay at 55 and it'll only be 78F max that day and not too windy, so that might help. If it looks like it's running too warm, I will go ahead and replace it in that city. The biggest hassle to me is draining coolant and repeated top offs as it burps out the air. Everything else is easy.
I don't have a new gasket on hand, so pulling it here is a bad idea, unless I was sure it was overheating, and I'd have to use RTV only. Total removal is for emergency purposes only, of which it's not one (yet) I don't think. I'll know for sure one way or the other Wednesday afternoon, now that I have a real temp gauge. I might just take the hour or more to do it at the Walmart there so I can lay that worry to rest if I don't like the temperatures I'm seeing.