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 494 TD-18, the balance being the well-known Caterpillar D-7 and Allis-Chalmers HD10W.
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, Germany, and Mr. Liucijus Suslavicius, Lithuania, for providing precious informations.