Brent ,
Even have the same laminated brass sheet-wood-brass sheet construction for the case.
A few FS6 sets have turned up virtually new , they seem to have been in stores then disposed of. I believe the FS6 was issued to the Indian army, a few have turned up in the UK, maybe ex Indian army stock ? . One notable user of these sets was the Northern Aust. observer unit, they were a unique unit . Usually a skilled bushman with horses would lug a FS6 and generator , batteries , looking for Japanese activity on the Nth coast, they camped in very remote places . They would wireless message to Darwin . There was a book somewhere .
http://www.lighthorse.org.au/resourc...-observer-unit