I have read that the BS turret, or fixed superstructure, made for the FT17 was seven-sided. The few photos I have found seem to show three plates on each side, plus the front plate. This implies that there was no rear plate. Is this interpretation correct?
The Renault 75 BS had a sort of box at the end. This contained (probably) a winch, as this tank was also designed to carry a trench crossing bridge in front of it, very much like the British Churchil bridgelayer of WW2. I will try to enclose the scale drawings I did some time ago, which were printed in Tankette, but as this is my first post, I am not too sure if it will work...