Great information, all. Many thanks.
Given that the frame is welded together, I assume the first step it is to remove what the Ford manual calls the "beam pivot bolt," which in this case is held on by a castle nut. Removing rusted old nuts is not my strength, especially not 1.5" ones. I bent a cheater bar last night, sprayed it twice with a lot of PB Blaster, waited 24 hours, all to no avail. Next stop is probably a torch on the castle nut, right?
Or am I heading in the wrong direction completely?