Apollo 6
The first stage of the Saturn V, S-IC, the third stage, S-IVB, and the Instrument Unit computer, arrived by boat on March 13, 1967. The first stage was put together in the Vehicle Assembly Building (VAB) four days later. The S-II second stage was delivered two months later. Scientist used a dumbbell-shaped spacer so testing could proceed. This had the same height and mass as the S-II along with all the electrical connections. The S-II arrived May 24. It was put into the rocket on July 7.