Something I noticed when reading the French archives at Vincennes: the APX-2 turret on the AMC 35 tank and the APX-3 turret on AMD 178 armored car both share the same turret ring diameter of 1395mm, and are two man. They have slightly different shapes, and the APX-2 was better armored and armed either with the full length 25mm SA34 gun, or the 47mm SA35, while the APX-3 had the shortened 25mm gun.
Judging by the shape of the turrets and the use of the same turret ring diameter, it should have been possible to modify the APX-3 to use the 47mm SA 35, or to put a more thinly armored version of the APX-2 on the AMD-178 for a similar weight. This, 5 years before the French would design a new emergency turret mounting this gun on the AMD.
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APX-2 APX-3
Interestingly enough, 1395mm is already a pretty large ring (55"), so it's possible the turrets could have been laid out to mount a bigger gun or a 3-man crew, or someone could have made new turrets with these characteristics on the same ring.