So I bought some model train stuff off a guy including a number of box cars with just the upper portion. New bottom or trucks. I don't seem to be able to find any bottom halves online to my surprise. Anyone know of a solution to this problem?
FWIW, if the suggestion to replace them with used stuff isn't in the cards, you could make boxcar floors out of basswood, attach Tichy bolsters, and slap plastic trucks on them.
Kadee #5 couplers with gearboxes to finish them up.
Better yet, Accurail sells boxcar parts, including floors and underbody details.