They built about 25k T72s, but those were built a while ago and not maintained. The last estimate I saw that seemed credible was that there were about 6000 T72s left. Let's say 1/3 are unusable, 1/3 are good for parts, and 1/3 can be repaired. That's still 2000 tanks - 20 more months of war, during which anything can happen.