I guess I will have to tell all of those motors I have rebuilt that I am not a mechanic. But wait Ford refers to it as an exhaust control valve. Heat risers are on top of the intake.
There use to be a rebuilt kit, but I do not see them any more.
I have one pulled running from a 53 and it is free. Doing a motor swap in a 60 F100.
I see it has bushings. but locked up. I have used the actetone and atf on mc stuff.