I know the consultant who designed these, and he specified etched open grid running boards and platforms on his plan.  That does not mean that the models will have such, but they were originally designed that way.  (I had nothing to do with the design of this model.)

However, the Society Tank Car book says “running boards were diamond tread steel and dome platforms were of open grid steel construction.” A photo on page 89 of that book clearly shows the dome platforms to be open grid. None of the photos clearly show the running boards. You have probably switched a bunch of these and may have photos that the rest of us don’t have. I would assume the open grid to be much safer to walk on.

Yes, the TK-N and TK-O were identical.

I wish manufacturers would proof this type of thing more carefully before going public. The initial Rapido ATSF RDC ad has some significant problems too that they know about but have not corrected.  

Maybe they want critics to point out the mistakes so they can get it right before production.