The insulator on the left is the size and shape of all my 104's with the exception of the one on the right. The left one is embossed "NEW ENG TEL & TEL./CO.", with no periods after "ENG & TEL". It has backwards "4" on dome. The one on the right has backwards "N's", and no periods at all. In addition, there is no spacing between words. Looks like this " NEWENGTEL&TEL/CO, with the backward "N's". How common/uncommon are these, especially the one on the right?