2nd picture in existence of this upgrade, this time clearly showing the tracks on the tanks side.

This is a T-54B equipped with so called "swamp tracks"; a very rare and (probably) one off upgrade to the T-54/55 series, where they added extended versions of the pre-existing tracks to traverse muddy environments, such as swamps.

Such tracks were most commonly seen on WW2 German Tanks, such as the Tiger 2, and they were less prevalent on Soviet tanks as a whole, especially post WW2.

This image was taken somewhere near Moscow in the 1970s, though the information is scarce.