I have found myself only this one and it is called X-33 VentureStar. As far I know these are two separate vehicles. X-33 technology demonstrator of VentureStar.
This addon craft doesn't fly well on Orbiter 2006P1 I have. Unresponsive to controls, I can't even approach and land with it
Unfortunately both crafts were canceled by NASA due to lack of technology to produce strong and lightweight fuel tanks. However has anyone developed full scale VentureStar in more detail? I truly hope there will be more complex addon - as this craft truly deserves to have a long life within Orbiter since it is most realistic concept (at least known to me) of single stage to orbit and reentry/land vehicle.