Distinctive shape of octave key touch. Linked LH palm keys - D# key lifts D key, F key lifts D# key and through it the D key, Note also the long slender shape of the palm keytouches, at a time when most US saxophones had round bulbous ones. The dreaded thumb ring is shown. The piece of cork was my attempt to make it bearable to hold and play. SN is shown (again, hard to read because the horn's been buffed to within an inch of its life).
I believe the SN is 201833.
The case I reckon is a replacement, but if it's an original Couturier/L&H, that'd be cool. I know it's not a Holton case. Also note the pivot screw. Very crudely made. The basic design is same/similar to Holton pivot screws. I have a Holton sax at home but have not done a direct comparison of the screws. Did Couturier use the same design? Or when Holton took them over did they move to using Holton small hardware? That would certainly be a cost savings, I'd think.
I will also point out that all the rods and hinge tubes are very much smaller in diameter than my Buescher or genuine Holton sopranos. The whole thing gives a feeling of general flimsiness.
The tone is rather nice, intonation is pretty good. The horn's in pretty rough condition and I haven't played it in probably 10 years, so it may not be very playable by now.