Here's a terrific look at one of the Omnibuses during the introduction of the wonderful Grand Canyon Diorama (which opened on March 31, 1958). It's the largest in the world, folks. Tell me you've seen a larger diorama. Can't do it, can you?
There was an auction years ago that had one of the strips of "mini posters" from the Omnibus, I sure wish I had made a bid! But that was from before the days when I even dreamed of owning an attraction posters. Those bus versions have to be terribly rare.