I have just done one Marx tender (as a test run to converting all tenders on freelance road to coal Vanderbilts), and didn't change its frame, but l have changed, lengthened and shortened, several RMT RDC and Industrial Rail trolley frames to power kit built or bashed gas electrics, with a Rock Island "motor" , Walthers gas electric , and a scale length Lionel RDC-3 yet to do, and l have used screws, brass plate, and epoxy for a strong frame fix. Really a lot of good ideas above, including the Dremel, unless you enjoy filling and sanding. Several roads used gas electrics almost identical to the Walthers "C&NW" kit, so l can proceed with it. Who has plastic Vanderbilt shells l can lengthen, shorten, convert to coal, if necessary, etc. I really like the looks of that long tender.
