I believe this to be a U-629 LOCKE with a large, upper case "E" that is not shown in the most recent VALUE GUIDE by Elton Gish. This insulator is a rich chestnut brown color as seen here. There are two bumps on the top of one ear. The "L" is barely visable when holding in your hand but shows up well with the flash on.

I'll post a second picture

All LOCKE insulators use capital letters in there embossing !

Thank you Elton