I have included two pictures. I believe it's a Mark-4F2 or Mark-4J or some other variant of a Mark-4. Can anyone ID for me? View attachment 13870
Don't hold me to this, but the main gun barrel length makes me think it is an F1 of the Mark IV. The next up F2 version had a longer barreled main gun to my best recollection, not the shorter barrel seen here. Don't hold me to it, I'm doing this as a WAG.
It is a German captured Russian T-34 that was recovered from a lake in Estonia in September 2000. Russian Tank Recovered from the Lake After 50 Years Been There | English Russia
It is definitely a T-34. This particular one is the "1943" model, since it has the hexagonal turret. This particular vehicle was probably produced fairly late as it has a commanders cupola, a feature introduced on the later vehicles of the T-34 1943 model line.