The modified MBTs can be easily differentiated, as they feature no IR illuminator and a "window" for the thermal imager on the turret. The observation system upgrades are among the key elements of the T-72M1R upgrade.
The upgrade included the installation of the KLW-1 Asteria thermal imaging system, along with a passive observation suite for the commander, and the gunner. The MBTs received by the Polish Armed Forces also featured a digital intercom/external communications suite by WB Group, a new navigation system, and other, minor upgrades.
#Ukraine: T-72M1 & T-72M1R tanks, 236 of which were recently delivered from Poland to UA, are already on their way to the front lines.— 🇺🇦 Ukraine Weapons Tracker (@UAWeapons) May 2, 2022
These are inferior (Particularly M1) to most Russian tanks, especially in terms of protection, but can still play a major role in future battles. pic.twitter.com/REBgnBMIBN
The delivery of modified T-72s is a major element of the overall support scheme addressed to Ukraine - these vehicles do not necessarily come from the surplus stock. The MBTs in question had been originally destined to be commissioned in the units of the Polish Armed Forces - some of them underwent modifications and overhauls, while some were to be reintroduced after they had originally been withdrawn. According to PLN 1.749 bn. agreement signed back in 2019 by a consortium formed by PGZ Group, ZM Bumar-Łabędy, and WZM Poznań, 230 MBTs were to be upgraded as a baseline, with 88 examples envisaged within the right of option.
The overhauls are taking place in line with a results-based formula, while the scope of work and the cost entailed depending on the condition of the specific vehicle. The number of MBTs transferred to Ukraine remains unknown. However, the imagery depicting the modified MBTs may suggest that a large pool of vehicles has been transferred - the IAR outlet's claims mentioned 150 to more than 200 main battle tanks.
One should also refer to the levels of capabilities. The Polish MBTs feature armour weaker than the Ukrainian T-64BW, not to mention the latest BM Bulat variant. The Ukrainian MBTs may also potentially feature a more modern, 2A46M(-1) gun, being better suited for engagements on the move, given the more advanced stabilizer they utilize. The Ukrainian T-64s also feature a different drivetrain. On the other hand, the modified T-72s feature much more modern observation instruments and a brand new comms suite. And the fact that extra MBTs come in a type that is well known to the Ukrainian tank crews also cannot be disregarded - following the two months of fighting, the recovery of losses is an utmost and certain necessity.