Next time I see the untouched original 1948 AD that's here locally, I'll make a point of looking at it. Unfortunately I didn't get his contact info. It's possible that the welds on mine were done after it left the factory. Unfortunately, the FAM has NOTHING on bed assembly. It's really hard to tell if the welds were factory, as there wasn't much left in the way of paint in that area on my truck. My truck had some strange modifications to the rear suspension, including some 6" pipe sections welded to the frame in place of rubber bumpers.
[On edit]
Here's a photo from Denny Graham's collection showing the weld at the rear cross-sill.
