Courtois 135G

[JC1951]

A few months ago, I bought an older Antoine Courtois Paris 135 G tenor Trombone, SN 9667. Judging by the condition it was in, it likely hadn't seen any use for decades. I surmised it to be an estate item being sold by descendants of the last user. After some tarnish removal and a visit to a slide repair and clean-up shop, it is now in top condition and sounds great. It's well built and heavier (7.9" Bell) than my old Besson 2-20. I have not been able to find out anything about it such as age and how many were produced, etc.

Is anyone here familiar with this model and could please comment?