Daniel: I did that decades ago with MDC/Roundhouse roller bearing trucks. Walthers was selling them as kits, just sideframes and (bad) wheels, for a fraction of what a MT truck cost. Since I didn't need the truck-mounted couplers, and Precision Masters wheels worked very well for me, I bought a hundred pair of the kits, a few bags of truck pins, and the PM wheels, all for less than good assembled trucks would cost. They ended up under all of my 100-ton cars, until true 100-ton trucks became available, because they were visibly larger than the MT RB trucks available then.