Although similar in appearance to the L-649 before it, the L-749 had a larger fuel capacity, strengthened landing gear, and eventually weather radar.

In early 1947, the Lockheed Aircraft Corporation unveiled the L-749, a derivative of its L-649 Constellation with fuel tanks to increase its maximum range by 1,000 statute miles (1,600 km).

In March 1947, 1,200 jobs were lost at Lockheed, bringing production of the aircraft to a near stand-still.

This was due to the end of military production from World War II bringing a reduction in the number of needed workers.

A cargo version of the L-749A based on the military C-121A was offered, but no airlines showed interest and it never left the drawing board.

An L-749B turboprop version was envisaged, but this too never left the drawing board as no reliable engine was found.