My father was going through his collection and came across this CD 154 Hemingray insulator. The front is marked Hemingray-42/ 8(1938) and 10 dots which would make it 1948. It is the short squatty mold in an off clear color round drip points. The back though, is the oddity. It is marked Made In U.S.A./ 6(mold number) and the letter "E". This is the only insulator we have seen so far with a letter after the mold number. Any idea of what the E stands for and has anyone else come across markings like this? Here is a picture of the front embossing. Very clean and neatly spelled.