Dealer Posters

Hi, im trying to find a little more info on dealer posters please. The registry states that 6s349 " is said to have been used on one of the original factory posters of 66 Shelbys". The picture attached is a copy of quite an old poster
i was given when i purchased the car. I have the original put aside. It has on the back handwritten 6s349 and someones signature - not CS. I was wondering if anybody had seen this poster before and could shed a little light on it's history or just advise on some detail of old shelby posters in general please. TIA. Cheers. Graeme.