Saturn IB
After the Apollo 17 mission in 1972, Pad 39B was used for Saturn IB launches. The Mobile Launchers were then modified for the Saturn IB rocket, by adding a "milk-stool" extension platform to the launch pedestal, so that the S-IVB upper stage and Apollo spacecraft swing arms would reach their targets. These were used for three crewed Skylab flights and the Apollo-Soyuz, since the Saturn IB pads 34 and 37 at Cape Canaveral had been decommissioned.