Jeffrey,
I believe the RMT, and KLine car bodies are the old Atlas molds from the 70s. The Klines sit way too high on the trucks. The RMT are a little better but still sit too high. The Atlas cars are still out there and ,when converted to Kadee couplers, look the best. The only drawback is the plastic trucks.
I did my own take-a-closer-look-see with my own K-Line and Atlas ore cars a couple of years ago and came to the conclusion that the K-Line version is actually a clone of the Atlas ore car tooling. Not surprising being they were tooled in China:
Note the K-Line above has four mold gates in the center, while the Atlas below has six. The K-Line cars sit high since the toolmakers in China also cloned the Atlas end-frames, which have a downward-projecting collar for the Atlas plastic trucks with a level bolster, rather than a flat bottom for the arched bolsters found on most 3-rail trucks. They could have removed the raised collar where the screw goes, but what do they know--they were likely told to "clone this car" and they did exactly that.
---PCJ
