The complete switch to tank production after the outbreak of the war caused a serious lack of artillery prime movers for the Red Army.
In 1942, the Lend-Lease deliveries, though increasing towards the end of the year, could not yet serve the ever growing demand of the front.
In an attempt to improve the situation, the engineers of the Russian NATI combined already existing components, the T-60/70 suspension and the GAZ/ZiS truck engines.
The Yaroslavl Auto Zavod (»YaZ«) was ordered to develop a new full-track prime mover capable of towing even the heaviest artillery pieces.
As a first result, the Ya-11 was completed in early 1943, driven by a GAZ-MM twin-engine, and until June 1943 the first 55 pieces were produced.
Among the aforementioned Lend-Lease deliveries were batches of GM 4-71 diesel engines with better performance than the domestic ones, so YAZ decided to further use them, resulting in 285 YA-12 high-speed tractor produced still in 1943.
As the new tractor proved quite successful, production lasted well beyond war's end with post-war vehicles using Russian engines again.
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