I have found no logical difference in journals between scale and 3-rail wheelsets. All the Atlas ones I have dealt with have the same axles, whether 2 or 3 rail. I have pulled the 3 rail wheels from some of the axles and replaced them with 2 rail wheels.
That is strange. Almost all of the 3-rail wheelsets I have replaced have journals somewhere around .070 in diameter. NWSL wheelsets are just a shade under .090 (I could look it up, but it is too early). I have not done any Atlas trucks, so maybe they are closer to NWSL. If you are using Atlas axles with scale wheels then you do not have to modify the Atlas side frame. And if you are using pointed scale axles in 3-rail sideframes, you are mis-matching, since most are set up for shouldered journals. That, and they will probably fall out, since scale wheelsets are narrower by a bunch.
It isn't a logical difference - it is a physical difference.
