It's hard to tell which car design they're building. White Pass has a bunch of 300 series cars with a few variations. 400's are the first class cars, 500's we only have a few of but they're the newest. The ends have a totally different collision post and they're longer than the 300's. None of the windows open for the passengers except the ones at each end of the car. This looks like something similar to the 500's which have a very small slide window for air in that little gap, but it's hard to tell.
John Hillier