S-IVB
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The S-IVB was the third stage on the Saturn V and second stage on the Saturn IB launch vehicles. Built by the Douglas Aircraft Company, it had one J-2 rocket engine. For lunar missions it was fired twice: first for Earth orbit insertion after... Wikipedia
Diameter: 6.60 m (21 ft, 8 in)
Empty mass: 29,700 lb (13,500 kg)
First flight: February 26, 1966
Gross mass: 271,000 pounds (123,000 kg)
Last flight: July 15, 1975
Manufacturer: Douglas
Successes (stage only): 20