JBL M40 15" speaker ?

[bkall]

Has anyone ever seen a JBL M40 speaker. The serial # is 10003 It is marked "custom manufactured by James B Lansing Sound Inc Los Angeles Calf. The 15" speaker is inside of a sano tube amplifier. I cannot even find a shred of info on this speaker

 

[toddalin]

Says M40 gets reconed with an E-140-8 cone, so should be similar specs.