mounted a 152 mm gun-howitzer on the chassis of a KV-1S heavy tank. (SU-152)
Later production used an IS tank chassis and was re-designated ISU-152
ISU-152 - 152.4 mm ML-20S gun (18 rounds) + 12.7 mm DShK anti-aircraft machine gun
ISU-152-2 - 152.4 mm BL-8 or BL-10 gun (21 rounds) + 12.7 mm DShK anti-aircraft machine gun
ISU-152 model 1945 - 152.4 mm ML-20SM model 1944 gun (20 rounds) + 12.7 mm DShK anti-aircraft machine gun + 12.7 mm DShK co-axial machine gun
IS tanks - a series of heavy tanks developed as a successor to the KV-series by the Soviet Union during World War II. The IS acronym is the anglicized initialism of Joseph Stalin (Iosif Stalin)