Super-Jupiter was the first-stage booster only; to place payloads in orbit, additional upper stages would be needed. ABMA proposed using either the Titan or Atlas as a second stage, optionally with the new Centaur upper-stage. The Centaur had been proposed by General Dynamics (Astronautics Corp.) as an upper stage for the Atlas (also their design) in order to quickly produce a launcher capable of placing loads up to into low Earth orbit. The Centaur was based on the same "balloon tank" concept as the Atlas, and built on the same jigs at the same diameter. As the Titan was deliberately built at the same size as well, this meant the Centaur could be used with either missile. Given that the Atlas was the higher priority of the two ICBM projects and its production was fully accounted for, ABMA focused on "backup" design, Titan, although they proposed extending it in length in order to carry additional fuel.