Thanks to Silverio in Patagonia, Argentina for this excellent picture!
There is a single pin for the right pinkie keys. And the register key hole has an older style button, instead of the little tube that protrudes into the bore. And Silverio has done a superb job in shining everything up so nicely! The mouthpiece pictured is NOT a Brillhart, but Silverio has taken a mouthpiece blank and made a facing like a Vandoren B40 Lyre series 13 Profile 88. Wow!
He says, “The bore of my clarinet is in top at the left hand = 14.95 mm. At the
botton = 14.85
(WAHHHHH IS POLICILINDRICAL same to Buffet R13 JAHHHHH)”
Silverio has found pictures of a LeRue metal clarinet with very similar keys, so this also reveals something about the approximate age of the instrument.
Silverio also reworked the register tone tube: “I make a reform of the standard pipe and use the sistem of Sir Galper.” [link: http://www.mytempo.com/register.htm] Wow! This guy has done some research!
Under the help for cracked clarinets page, you can see how he fixed a crack in the barrel!
Because of the register key and left pinkie keys, I would guess this is a Couesnon product from the 1930s.
Silverio has added pictures that show all of the key work. I haven't had time to verify if this key work is most likely Couesnon or not. He also sent a really neat recording attached below. Great jazz sound, Silverio!
Silverio also sent this link to a Woodwind.org discussion of another E. Lerue.