The only "clue" I can see is the "octagonal" knobs.
On B6 steels ... one octagonal volume knob was on the audience side ... on '35 and '36 specimens.
On early spanish B6s ... the one octagonal volume knob is on the player's side .
They put tones on steels ... around '37 ... opposite sides ... "Arrow knobs" though.
Another clue that the seller could check is the stamp on the "half moon" mounting plate (under thumb/knurl height adjustment nut).
If it says "patent pending" its pre-August '37
If it has the "serial number" its post-August '37.
I'd
guess ... early 1937 ... cause of the octagonals on opposite sides ...
Just a guess ... best I can do.
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