Roco T-34/57

Take a Roco T-34/76 turret.

Cut off the gun barrel and replace it with the 57mm gun from a PSR 57mm / 76.2mm ATG kit.

File down the side angle a bit and then take the pistol ports from a Permit tank kit and glue them to the turret sides.

Cut off the cupola and replace it with a hatch made out of sheet styrene.

Take some plastic rod and make the ventilators for the rood; instant T-34/57.