SHS cars (there are many of them out there mint in box) come with additional scale wheels in a little bag that also contains truck plates. Those replace the ones that are part of the AF couplers. Without those distance pieces the car will ride too low above the tracks. Kadee couplers you have to buy seperately but you find sockets with pre-drilled holes at the bottom of the cars.?
Older AM cars are a bit different. The socket fits the elder standard for Kadee #5 (just one screwhole). If you use Kadee #802/808 you will have to drill additional holes. Having never bought AM freight cars new I cannot tell if they come with scale wheels. The ones I bought used had scale wheels on them. Interesting detail: The distance plates and the trucks look exactly the same on SHS and AM.
A few of my used cars have hirail wheels. I shall buy NWSL wheelsets for them but as long as my only trackwork is S-Trax I'm in no hurry at all.
Addendum: Not long ago I ordered a set of sergent couplers and shall report about their functionality when they arrive from China. To convert the whole fleet would be still doable but expensive yet. So I will experiment a bit...
Kind regards from Middle Franconia, Hans
