Ok all these trains are basically the same internally design wise. The 47/48 have a stronger planetary set in them but it is interchangeable into the 518/46 models. I have a 518 that I am tearing down now for a rebuild. The trains as of rite now needs a front planetary it is aluminum and only 4 pin design that's not going to work for me upgrading to steel 5 pin set. The rear planetary I cannot get to yet as there is what they call an 800lb spring that requires a press to get out. This is not a step that in anyway can be or should be done without a press it can kill you! Look at this thing