Johnson Space Center has one of three remaining flight-worthy Saturn V rockets in the world. Of those three, Johnson’s display is the only one that consists of flight-worthy stages. Displays at Kennedy and Marshall consist of a mix between flight-worthy and test stages.
Its first stage is S-IC-14, second is S-II-15, and third S-IVB-13. The first and second stage of Saturn V-13, S-IC-13 and S-II-13 lofted the Skylab space station to orbit. Since the orbiting workshop took place of the vehicle’s third stage, S-IVB-13 remained on the ground.
Boilerplate 115A represents the Apollo spacecraft, and was an unused test vehicle.
Skylab orbital (enhanced ‘workshop’) : museum visitors to Space Hall gain access to the viewing port via scaffolding stairwell then enter Skylab’s capsulate interior where they will find an observation chamber and interplanetary exploration simulator.