Thank you folks for the information you all provided.
John, the term or trade-mark MARK 5 identifies and relates to a plastic sheet, or collar, that went around the shot charge in the shell to protect the shot traveling down the barrel. I believe it preceeded the Remington POWER PISTON one-piece plastic shot cup and wad system. It was used in paper hulled shells for a couple of years before they introduced the plastic Compression-formed hull. The box on the left is the paper but the Warning label on it seemingly makes it newer than I suspected, if Ron’s date is correct. The label in question, on the inside of the box, is a type of code but I had it interpreted by a former employee of the store but it is quite possible that he is wrong. He worked there later and all of the people working there at the time have passed on. I would venture that the paper hulled Mark 5 probably came out in 1961 or 1962 because I recall they were only out a year or 2 before the plastic hull came along.
Now as to the plastic hulled shells, the right hand box, I guess we can date it’s earliest birth as 1964. I know from personnal experience that these shells, with the Mark 5 collar, continued into the 1970’s and were offered in the Super-Speed, Super X, Xpert and Ranger brands.
Here’s a scan of the bottom of the box that might interest you all.