The model comes with the standard A.C. Gilbert American Flyer-compatible oversized couplers and hi-rail (tall-flange) wheels.
However, the box includes the Kadee-style S-scale couplers as well as replacement wheelsets with code 110 wheels. This photo shows what the underside of the model looks like after removing the AF-compatible trucks (those couplers are truck-mounted). You can see the mounting holes for the Kadee-style coupler molded into the coupler pad. The brake system details are adequate and the wood-grained floorboards are a nice-to-have feature. The rivets are visible on the bolsters. In other words, it is not an embarrassment to turn these cars over when showing them to your railroad buddies.
Installing the couplers was near trivial. The box comes with thin shims that can be installed between the coupler and the body. The only problem I had was with the replacing of the wheelsets. The ACL model has three springs in their trucks. I tried the twisting of the sideframes approach to pop out the wheels, but was unable to do so. Next, I tried removing the springs from one of the sideframes, which makes it possible to remove the sideframe, put in the wheels, and then reinstall the sideframe. The problem with that approach was that the springs are next to impossible to get back into the trucks. I could get two of them in there after much effort, but when I tried to get the third one in there, one of the other ones would pop out again. Out of frustration I finally gave up and simply replaced both trucks with a spare set that already has scale wheels installed. I may try to tackle this spring issue again in the future.