As they were first built, the "D" model was virtually identical to earlier models of the aircraft except that it lacked the reconnaissance ability of earlier B-52s and was intended purely as a bomber. In 1965, modification of B-52D aircraft began to increase their conventional bomb load. The "Big Belly" modifications resulted in the ability to carry a total 108 conventional bombs both internally and externally. Markings displayed by this machine: 7th Bombardment Wing, Carswell AFB, Texas, 1981