After the war Boeing developed the Model 367, a military transport based on the B-29 bomber. Its civilian counterpart was the 377 Stratocruiser. The C-97 was designated KC-97 when it was equipped with the Boeing-designed flying boom for aerial refueling. There were 888 C-97s built between 1947 and 1958. Of those, 219 were adapted as KC-97E and F tankers and 592 were KC-97G models. The KC-97Gs had additional 700-gallon external fuel tanks under each wing and could dispense 8,513 gallons of fuel while carrying 96 troops. Sales of the KC-97s helped pull Boeing out of the post-war slump, and because they extended the range of bombers and fighters, the KC-97 tankers became crucial to SAC operations.