"Diagram of equipment locations in the fighting compartments of the IS tank and KV tank with IS turret, armed with a D-5 gun"
CAMD RF 38-11355-1529
The gunner sits on the left, the loader sits on the right. The commander sits behind the gunner, underneath the cupola. A radio is positioned right next to him. Ammunition is stored in a case behind the crew, in the rear of the turret. The rectangle in the center is the gun.
The images on the bottom are views from the side, showing the "KV-D5" (left) and "IS-D5" (right).
"Diagram of equipment positions in the KV tank with an S-31 gun"
The layout of the KV with an S-31 (Object 238) is similar to that of the IS tank. However, you can see one major difference that proved fatal to the project: the gun is only 75 mm away from the turret ring, unlike the D-5, which enjoys 430 mm of clearance. Because of this, the commander's position must be shifted to the left, leaving no room for his radio.