Here's an insulator I discovered at the Yorktown Show. Never seen one like it. The photo shows a CD 152- CD 153 - and a CD 154. The 48-40 has always been found and classitied as a CD 153, which the center one is. The one on the left though, is a CD 154 with the 48-40 embossing. Not listed in any book or guide that I know of.