I am surprised that MT is confusing the issue the way they are. The number is clearly the rebuilt Pullman parlor car 755, which they could have more accurately modeled with their parlor car model. If they wanted a stand in for the Bethlehem cars, which were single window (AFAIK), it would seem to make more sense to wait a couple months until their single window car body is in production.
Well, I guess I will never understand marketing departments, and marketing departments will never understand me.