To empty, open the bottom doors and shake:
The added side beams on these modified boxcars replaced the structural components lost by removing the roof and cutting away parts of the underframe to install the doors.
Thanks for that knowledge on the underside beams, that makes great sense. In looking at the photo I posted again, I am wondering if, given how far those new side beams come out past the center of the trucks, if these cars would be modelable.
As for the door opening, well you explained when the doors should be opened (when you want the load out, duh) but not how those "wheels", or whatever they are, on the side of the car work. By the positioning of the carman in your pic, it looks like a handle/lever is being inserted to turn it, like a wheel, or release it, as a ratchet. That's what I am trying to figure out, what is the mechanism that opens the doors. It's just, to me, those round things on the side of the car don't present as big enough to be wheels that can be turned without assistance (like a brakewheel) to slack a chain that frees a door open; they look like a pulley to me.
OOC, did the Southern ever recreate this design in a 50-foot car?