Just a small date correction:
unit 12 (T-34/85) should be available from March 1945 (not June)
source: Bojan Dimitrijevic, Modernizacija i intervencija: Jugoslavenske oklopne jedinice 1945-2006, beograd 2010 (in Serbian language only)
This information can also be found at Wikipedia:
https://en.wikipedia.org/wiki/First_Army_%28Bulgaria%29