The further improved BGM-71D TOW 2 was first delivered to U.S. Army and USMC units in 1983. It has a still larger and heavier warhead, which increases the diameter of the warhead section to that of the main missile body. It also has a slightly longer nose probe, an improved double-base rocket motor, and a new countermeasures resistant digital guidance system. Armour penetration capability is increased to about 800 mm. Although I haven't found any reference to it, there is probably also a BTM-71D training round for the TOW 2.