Widely unknown, the Soviet Union received some 7,500 track-laying tractors through Lend-Lease during WW2, the three main producers being Caterpillar, International and Allis-Chalmers.
While the bulk of the crawlers were of the light and medium type, over 1,000 were heavies.
Among the latter were 415 HD-10W out of 747 produced by Allis-Chalmers in Milwaukee between 1940 and 1943, the balance being the well-known Caterpillar D-7 and IHC TD-18.
The Red Army instantly deployed them to their heavy artillery units where they excelled mainly as prime movers, e.g. during the fierce Carpathian mountain fightings of 1944.

Special thanks to Mr. Michael Franz and Mr. Jochen Vollert, Germany, for providing precious informations.