Several Saturn IBs also remained unused and in storage at the end of the Apollo program. Three (SA-206, SA-207 and SA-208) were used for the manned launches of the Skylab program, and SA-210 was used for the manned ASTP flight. The second stage of SA-212 was rebuilt as the launched Skylab. Of the remaining vehicles, two are on display, and the rest were scrapped. Any surplus Rocketdyne H-1 first stage engines were rebranded as the Rocketdyne RS-27 engine for usage on active launch vehicles of the time, such as those of the Delta 2000 Series in 1974.