Is there a number printed in the other side?
Probably a silver inked "L1" next to the terminal connected to the outermost winding of the voice coil. I wouldn't expect to see anything on the topside unless it was a later pascalite, those had "909" and the maestro inked right on the aluminum dome, i'm betting you've seen them before.

Some part numbers were stamped on the inside circumference of the paper voice coil former

http://i107.photobucket.com/albums/m...sympasfrnt.jpg

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Quote Originally Posted by cradeldorf View Post
Probably explains why was mine missing after it went to GPA.
Sorry to hear of this. I feel fortunate that i was advised long ago to NOT send working diaphragms or salvageable cones when having anything rebuilt as you will not see them again.

It is also a good idea to tape a note to each component specifying the exact work you want done to it. There's just no substitute for good communication.