Short answers, pulled from the story.
Pratt and Whitney Rocketdyne was an American company that designed and produced liquid-propellant rocket engines. It was a division of Pratt and Whitney, a fully owned subsidiary of United Technologies Corporation, headquartered in Canoga Park, Los Angeles, California. Its products included the RS-25 Space Shuttle main engine, the RL10, the RS-68, the J-2X, and the SJ61 scramjet.
Pratt and Whitney Rocketdyne was formed in 2005 when Pratt and Whitney Space Propulsion and Boeing Rocketdyne Propulsion and Power were merged after United Technologies Corporation acquired the Boeing division. Boeing retained the 2,800-acre Santa Susana Field Laboratory property above Canoga Park as part of the transaction.
In July 2012, United Technologies Corporation agreed to sell Pratt and Whitney Rocketdyne to GenCorp, Inc., which also owned rival rocket engine producer Aerojet. The sale closed in June 2013, and Pratt and Whitney Rocketdyne was merged with Aerojet to form Aerojet Rocketdyne.
The RL10 has been used on the Saturn I, the upper stage of the Delta IV, the Centaur upper stage for Atlas and Titan rockets, the McDonnell Douglas DC-X Delta Clipper, the Atlas V, the Vulcan Centaur, and the Space Launch System Block 1. It is planned for Space Launch System Block 1B and Block 2 as well.
The RL10 was designated an American Society of Mechanical Engineers Historic Landmark. The designation was granted to Pratt and Whitney, which originally developed the liquid hydrogen and liquid oxygen engine.
The SJ61 was a dual-mode ramjet and scramjet engine that burned JP-7 fuel with ingested air rather than a stored oxidizer. It flew on the Boeing X-51 hypersonic demonstration vehicle and represented a departure from the liquid-propellant engines that formed most of the company's portfolio.