I bought a 80s vintage Right of Way Industries brass B&O wagon top boxcar a while back . Someone had tried to mount a late 90s sound of steam system in it but the old lionel boxcar frame did not fit and I wanted to install the modular Railsounds 4 boards in a tender anyway. So my brass ROW wagontop did not have a frame or trucks. I have dozens of the old 70s vintage Atlas O scale freight cars and I decided to rob the frame off one. It was slightly to wide so I took a sanding block and took a couple thousands of each side till it was a snug enough fit that it would hold itself in place. I had some foot stirrups so I drilled through the new frame into a mounting plate the original floor was screwed to and used the screw holding the stirrups on to hold the floor on also. Anyway this is how it turned out.