I have six of them -- two in 2-rail with the couplers replaced with Kadee 746 long-shank, one as a transition car (literally 2-rail on one end and 3-rail on the other) and three 3-rail. This is the only video I have that shows them going through curves. The lead flat is a "transition car" from 2-rail to 3-rail (the locomotives have scale wheels and Kadees). The curve going into the tunnel is Gargraves O-72; the track on the bridge is Gargraves O-96. As you'll see, there's quite a bit of underhang on the 89-foot flats, but because of the wheelbase, the 2-rail cars will make it through O-72 even with scale wheels since long-shank couplers with longer swing are used. A word of caution -- these cars are very heavy as they're die-cast, so despite their length they should be at the front of the train. If you're going with the 2-rail cars, ditch the plastic long-shank couplers and install Kadee 746's.