I had a look through my analysis notes last night. All that remains of what you have labeled as Vent #38 is the reinforced pad upon which the vent/fan assembly once sat. The decks underneath have compressed together, so nothing can be seen from the side.
There is a row of rivets running athwartships just forward of the outlines of the vent foundation, and another just aft. These rows of rivets continue with equidistant spacing forward and aft of this area. A railing stanchion base sits at the roof's edge, lined up with the forward edge of the vent foundation.
Inside the foundation area itself, two holes in the deck can be seen. One, in the forward starboard quadrant of the foundation, is irregular and is possibly a corrosion hole (there is a larger irregular hole forward of this outside of the vent's foundation). In this hole, there is something thin running athwartships...is this the frame? I could not verify from the one image in which it appears...the other images of this area show the entire hole as black.
The second hole in the foundation pad is not irregular. Three of the four edges are straight and the curved corners are sharp. It is longer longitudinally than transversely, runs along the outboard (port) side of the foundation and is not centred fore-and-aft, but rather slightly forward. This would be the vent ducting pass-thru. There is debris visible in the hole, but none of it is identifiable. It does not appear that the thin object seen in the first hole extends through the second hole.
That's the extent of my notes on this particular area.
Parks