Though photographs of vehicles in Russian service exist, it's not yet totally sure that among the 500 British Austin trucks, delivered to Russia from late 1941 to 1942, were Austin K2/Y Heavy Ambulances.
According to Beaumont and Vanderveen, the British provided ambulances to the Russians, but the vehicles in question could as well have been German ones, captured from the BEF in the West in 1940 and pressed into Russian service after their resp. capture by the Red Army.
Anyway, 13,000 K2 Ambulances were produced throughout the war, each one capable of transporting 4 stretchers or 10 sitting soldiers.