http://www.xcor.com/press-releases/...ter_Selects_XCOR_and_LYNX_for_Suborbital.html
As far as I can tell, the main difference between Mk I and Mk II is that Mk I has an apogee of around 60 km, whereas Mk II has an apogee of around 110 km. Externally they are the same size/shape although the Mk II may use a strap on booster.The Yecheon Astro Space Center announced today that it has selected XCOR Aerospace as its preferred supplier of suborbital space launch services. Operating under a wet lease model, XCOR intends to supply services to the Center using the Lynx Mark II suborbital vehicle, pending United States government approvals to station the vehicle in the Republic of Korea.