The PRR diner (along with a former coach) is now used for birthday parties; but, years ago the UP heavyweight diner was used for the birthday parties.
I do recall that the PRR car was called "Coach of Fame." The website for Travel Town does not provide any information. But, the photo of the car taken years ago at Travel Town does seem to show some lettering in the center below the window. I think the car was set up for some kind of display instead of retaining the dining car tables and seating.
Here is a photo linked from the Travel Town website that shows the interior of the coach and the dinner used today for birthday parties. I think the coach came to the park without interior seating and was used early on for some kind of exhibits. One of the coaches (or both) had built-up Ravell models.
And here is a photo of the diner years ago at Travel Town linked from the information page about the dinner:
It is rather late at night to do more research. When I do -- or find other information -- I will post it.