D-10 tank gun
...that the Soviet D-10 tank gun of World War II was built until 1979 for the world's most common tank (the T-55), which remains in service?
...that the <a class="mw-redirect" href="./Soviet" id="mwBf8" rel="mw:WikiLink" title="Soviet">Soviet</a> <b id="mwBgA"><a href="./D-10_tank_gun" id="mwBgE" rel="mw:WikiLink" title="D-10 tank gun">D-10 tank gun</a></b> (<i id="mwBgI">pictured</i>) of <a href="./World_War_II" id="mwBgM" rel="mw:WikiLink" title="World War II">World War II</a> was built until <a href="./1979" id="mwBgQ" rel="mw:WikiLink" title="1979">1979</a> for the world's most common <a href="./Tank" id="mwBgU" rel="mw:WikiLink" title="Tank">tank</a> (the <a class="mw-redirect" href="./T-55" id="mwBgY" rel="mw:WikiLink" title="T-55">T-55</a>), which remains in service?