That's interesting. My truck (a '51) has no bolt back inside the hinge pockets, and the hole in the pocket has no provision for a cage nut. Maybe there was one on earlier trucks, but I can't verify that.
I just started alignment of my doors also and noticed that my ‘52 is also missing the back bolts on the hinge pockets. I remember reading on this forum about not forgetting to loosen those bolts. I thought one of the past owners, snapped off the cage nuts at one time and I would have to reinstall them sometime in the future. Seeing proof that the ‘47 has the cage nuts and mine and Kevin’s do not, I question whether or not my ‘52 should also have them. I leaning on the side that they should be there.
We need some of the seasoned ‘bolters to chime in to set the record straight!