Hmm, not mine.
Was just coming here to see if anybody knew how the top plate was attached. I wire-wheeled the top surface hoping to see the spot weld dimples if present, but with the rough surface, no luck.
I see some edge seam stitch welds, but it doesn’t seem likely that’s all that’s holding the arm together.
It’s worth noting there were extensive repairs by “some other guy”, featuring lots of angle iron, an upside down kingpost truss under one rocker, galvanized roof tin, repurposed steel from other car bodies, and lots of rivets. It’s possible these X-arm top plates were added, but I’ve found them under original, unpatched floor so it seems unlikely.