It's simple.
T-72B (Object 184) can be seen with or without 4S20 Kontakt-1 ERA, there is also T-72B1 (Object 184-1) variant, as T-72B can have or not Kontakt-1, and use simplified FCS without 9K120 Svir system for 9M119 Refleks GLATGM's.
T-72B tanks manufactured somewhere between 1988 to 1989...