Brute Force by John Ellis is a good book about the war detailing the impact of Russian front and overall allied production.
The US provided the Russians with transport vehicles but their tanks were primarily Russian.
A German General in the early days of Barbarossa, saw the T-34 for the first time, and remarked that if the Soviets could mass produce the T-34, Germany would lose the war.
Well, we also sent them Shermans. And the UK provided a few (466) Churchills.
“Most visibly, the United States provided the Soviet Union with more than 400,000 jeeps and trucks, 14,000 aircraft, 8,000 tractors and construction vehicles, and 13,000 battle tanks”
So we sent 13000 tanks. Keep in mind that the USSR produced 60000 T-34s. So we provided almost of 18% of the Soviet medium armor. I would say that was ‘substantial.’