Hello,
These boxcars are listed as Premier on the product webpage and they are under that category on the archive site as well. I was under the impression that this was a brand new tooling from Atlas, so I would expect them to be in the trainman or master product line. Was this a product under development by MTH that is being released by Atlas or was this just an accident. This is mainly a question for @Paul Graf, but I imagine other people will be interested in knowing the answer. Thanks.