On the left is the unknown threadless insulator that was on eBay a couple of weeks ago. I have taken a picture of it along side my CD 728.2 NN Beaver Falls piece. The unknown insulator is 3'' x 3- 3/4". As one can see, it is slightly smaller than the CD 728.2 that I have, but not by much. It also has a MLOD. What do I have here? I was leaning towards the CD 728.7 . Should I be so optimistic?