RS-68 from the Delta IV?
http://www.boeing.com/defense-space/space/propul/RS68.html
It is not "Man Rated", (But then, neither is the Vulcan 2) and seems to weigh about twice that of SSME, but has close to 25% more thrust, and, according to the Boeing/Rocketdyne site “a simplified design philosophy resulting in a drastic reduction in parts.”
Just throwing it out there.