Here is what I did to make the observation car. Originally I was hoping MTH made an observation car in a 60 footer that already had a platform and I could just cut the platform off and install the Lionel one. But nope! They only make cars like that in the larger one and the smaller one so I had to cut the back off of a passenger car and then I cut the back of of the 60 footer observation car. I liked the door and Windows of the non platform observation car so I cut it and used it to make mine. I hated to do this because I wasted that car completely but I knew I'd never use it.
Now keep in mind I had dreams of grandeur, and wanted to make a observation car like Keith's. But I've got a 3 year old and an infant, with limited time and I still don't know if I'm talented enough to do what Keith did so this is what I ended up with. I like it and it's around as good as what you'd get from Lionel as far as being close to looking like the observation car in the movie. I still would like to make another one that has the curved roof in the rear with a light, so maybe by next Christmas it would be ready. I also ended up cutting the two posts for attaching the roof in the rear that are visible in the building stage pictures. I found another way to hold the roof on in the back there. Totally fun project and to think this all started because I bought the lionchief set for my sons first Christmas. There are so many great people on here to help with questions it's a great hobby!