I'm really sorry if I'm getting these "placements" wrong, I'm not really familiar with tanks.
no problem man. i was just talking about how tall the turret ring is. if you don't know what a turret ring is. it is what holds the turret up and allows it to rotate. in this case it is the round bricks that you built the turret on top of. however, if you were to make it shorter, the gun would collide with the raised back of the tank (if you were able to actually it.) just a tip to make your build that much more realistic.
i am getting really nitpicky though. either way, you still did a fantastic job on all of these tanks.