I wouldn't be surprised to find out that truck swaps were done... after all, the frameless tank cars were originally standard gauge cars and after being modified to fit the narrow gauge trucks, the bearing blocks for the fat gauge trucks were retained... might have been a rather simple task to disconnect the brake rodding, roll the narrow gauge trucks out and roll a fat gauge truck in and hook it up. The E.B.T. did the same using their timber transfer in Orbisonia (I think... feel free to correct me if the timber transfer was located elsewhere...)