The sign was still there in some of the rooms on the New York Central line ca 1957. As most other "equippage" apparently intended to be present was also only sporadically in place, it might be assumed that it was intended to be in all the cars.

I don't recall it being on the AT&SF train on which I made the other half of that particular trip. Most of the Santa Fe equipment was apparently much more recently built, incorporating "more civilized" features similar to cross-country buses of a later era.

John