Ed I have converted my MTM tank cars to Kay-Dee..as for USA I have no clue.
What you need to get is some various widths of Evergreen plastic..BUY a Kay-Dee coupler gauge, and just do it. Once you do 1 or 2 they start to get easy....
What you will need to do with the gauge is see where they align with the gauge and then use shims of plastic to get at the proper height so as not to have unalignment between the couplers....the Kay-Dee gauge is the standard for alignment for all brands of trains..at least it would seem to be so.
Maybe, we should get together and I can show you how to approach mounting ANY coupler brands!
BUT you have to come to my house to do so...it is easier to show you then to add pics and use verbage....maybe make a list of everything you have questions about then we can get together and you can take pics for later reference as I do...and I can answer all your questions...OR set multiple times to get together to do so...after all you are in a club with all this info redily at your hands for asking....this is what a club is for!
It seems that the coupler question keeps comming up here on MLS more so then other questions....and it is one of the easiest to remidy...with a little help.
First and foremost get a Kay-Dee gauge..it has 3 gauges that come in handy...1 for coupler height, track width and wheel width.....get multiple packs of various thicknesses of Evergreen plastic various size screws, super glue, and black paint to paint the shims after using them to blend in.