This Drums & Crates set includes a Soviet Stalinets-2 tracked artillery tractor plus a M1931 B4 203 mm tracked Howitzer, also called "Stalin's Sledgehammer".
This is partial text from the full article (usually with photos) at https://armorama.com/news/1-72-soviet-stalinets-2-m1931-b4-203-mm-howitzer-from-drums-and-crates