I found this Hemingray 45 with a date code that translates to 1970. This is three years after the last insulator with the Hemingray name was supposed to have been made at Indiana Glass. I requested information and received a reply from Woody Woodward. He said that he never had any indication that any insulators were manufactured after 1967 and a mold engraver may have just added extra periods to the date code for whatever reason. He also said that it is unlikely that Indiana Glass bothered with dating these insulators, in which case the engraver could add extra periods to the date code and the insulator would still pass inspection. So it looks more unlikely that this one was actually made in 1970. Thanks to all who have expressed their interest in this.