Thanks to the response from "Slade", I am inside my 1X15 cab. I believe the speaker is not original. It has no name on it, and looks pretty new.
There is a number on the frame: 55-560 1090994
There is a number on the paper cone:506807-1
Anyone care to hazard a guess as to who made this speaker, and when?
Thanks for all the support. You guys have been great helping figure out my Sunn.