Rare Johnny Cash Promotional Poster for Lionel Trains?

Saw this exact poster hanging in a train store and asked the owner about it. He said that it was only issued to model railroad train dealers. At the time, my son was really into model railroading and I wanted this poster for his train room. I searched the internet for months until I finally had somebody say they had one. Both the owner of the train store and the gentleman I bought it from said it is extremely rare. Possibly no more than 70 in existence. Not sure how true that is, but it would be great to have some more information on this poster.