And a T-13
B3, which was sufficiently redesigned from the B1 and B2 versions to make identification difficult (virtually a completely different tank); the B3 version lengthened the hull, added an idler wheel and track return rollers to the suspension, increased the depth of the hull superstructure, and replaced the turret, which was given a full 360° arc of fire, instead of being able to fire only over the rear deck, as in the previous versions:
T-13 B1:
T-13 B2:
Having only found the B1 and B2 illustrations, you can understand why I thought 'close, but no cigar'...
Looks like it's wearing hand-painted German markings -- the old plain white Greek cross that was used for German vehicles during the invasion of Poland. That would make the tank a Panzerjaeger (Sfl) CL 801(b).