This is from my old post in the old forum but I have added T-55s too.
Finland has operated multiple T-72 variants, however mainly the T-72M1, T-72M1K and T-72M1K1 tanks.
Also ontop of those there have been many variants, example.
I have made the variants id like to see ingame in bold.
-1 variant with Diehl rubber tracks,
-1 with a Russian V-84-1 840hp engine with the exhaust modified to go backwards (i.e. from the rear and away from the tank),
-1 with a Polish S12-U 840hp engine
-1 with a Finnish Wärtsilä 1000hp engine and French RENK AG ESM 350 transmission, for 8 forward gears and 3 reverse gears. Allowing speeds >20 kmh in reverse for example, also capable of neutral steering.
-at least 1 with FINMOD 1 modifications i.e. new FCS like in the Finnish upgrade of the T-55M, new ammunition (Penetration between DM33 and DM53), and thermals
-1 FINMOD 2 modification i.e. everything from first one, same from earlier upgrade but with ERA, warning syste, slightly upgraded armour and weaponry.
And those are the currently known off Finnish T-72 variants.
Video of the T-72 FINMOD 2 prototype
Finnish T-55 with Polish AM armour.
Finnish T-55M with apparently German AMAP armour package, tank nicknamed Dolly Parton.
Sources:
Panssarikilta magazine about the T-72 in Finland, I have the pictures of that magazine available
https://fas.org/man/dod-101/sys/land/row/t72tank.htm
https ://www.youtube.com/watch?v=JUa_WBQaJNc
Suomalaiset panssarivaunut 1918-1997 : The Finnish armoured vehicles 1918-1997
Olli Diehl - The man who made the presentation of the T-72 FINMOD program, some parts of it is classified and are not shown here.
Patria - Company that was to upgrade the tanks to the FINMOD standard
https ://www.youtube.com/watch?v=X3LXoG3BWyI