I am a fairly new N Scale modeler. All of my rolling stock so far has had Micro Trains of Accumate couplers but I just acquired a WALTHERS Stand Alone Well Car that has Rapido style couplers, and I want to replace them. MTL seems to have quite a few choices is there a standard reference that tells which couplers go on what style cars? I just need to know which couplers to replace these Rapidos with.