 On the T-55 the D-10 continues to be in active service in many countries.At the beginning of 1944, the T-34 tank's F-34 76.2 mm tank gun was replaced by a more powerful 85 mm gun.This rendered the year-old SU-85 tank destroyer effectively obsolescent, since its D-5T 85 mm gun was now also fielded by a more flexible medium tank.