The oldest operational piece of rolling stock I currently have is an old Mantua U. S. Navy 40' flat I bought about 1954 It originally had body mounted Mantua horn-hook couplers, but now has a pair of truck mounted Kadee magnetic couplers. Just didn't want to try filing or machining down the sloped ramp for body mount. I still also have some parts, frame, drivers, cylinders, motor, from the Mantua Booster 0-4-0-T I bought at the same time. Also still have a couple pair of passenger trucks from old Globe (later Athearn) passenger car kits I bought a few years later. Oldest kit built car I have is either the wood body from an old Strombecker coach (had to replace the card sides with scratch built sides) or a Mainline all wood Pullman Palace chicken car. Almost matches with the slightly newer Ambroid chicken car I built in the 1960s.