I don't have many of the old Max Gray/USHobbies #401 48' mill gondolas with drop ends (mostly the more-common prototype 52' fishbelly #402's), but I finally got around to improving one and have exhausted my standard references for prototype, so I throw myself on the mercy of the list. I am not asking for exhaustive research, but perhaps someone familiar with them on a favorite road could point me in the right direction.
Jace, most of us on this list are in HO scale and don't have any idea what the Max Gray model looks like. If you could post a photo or two in the list archives, we might be better able to help.
