Rocketdyne
The Rocketdyne Division was founded by North American Aviation (NAA) in 1955, and was later part of Rockwell International (1967-1996) and Boeing (1996-2005). In 2005, the Rocketdyne Division was sold to United Technologies Corporation, becoming Pratt & Whitney Rocketdyne as part of Pratt & Whitney. In 2013, Pratt & Whitney Rocketdyne was sold to GenCorp, which merged it with Aerojet to form Aerojet Rocketdyne.
Rocketdyne E-1
Rocketdyne's E-1 was a liquid propellant rocket engine originally built as a backup design for the Titan I missile. While it was being developed, Heinz-Hermann Koelle at the Army Ballistic Missile Agency (ABMA) selected it as the primary engine for the rocket that would emerge as the Saturn I. In the end, the Titan went ahead with its primary engine, and the Saturn team decided to use the lower-thrust H-1 in order to speed development. The E-1 project was cancelled in 1959, but Rocketdyne's success with the design gave NASA confidence in Rocketdyne's ability to deliver the much larger F-1, which powered the first stage of the Saturn V missions to the Moon.