Chris Gebhardt of NASASpaceflight wrote a great rundown of Orbital ATK’s Next Generation Launcher that included this little nugget at the end:
On 16 April 2018 at the Space Symposium in Colorado Springs, Colorado, Orbital ATK will unveil the official name for NGL as well as the engine that has been selected for the cryogenic LOX/LH2 third stage.
The upper stage engine news will be quite interesting, especially in light of the recent Blue Origin news. Blue Origin’s BE-3U was reportedly dropped from the competition a few months back, leaving Aerojet Rocketdyne’s RL10 and ArianeGroup’s Vinci as the finalists. I’m really curious how these two decisions are related, if at all.