This shows the installation of the ADAHRS (Air Data and Heading Reference System) box in the tail cone. I believe this location is selected to keep the device far away from the steel and electricity (magnetic fields) in the avionics and engine area. The other steps on this page are the connections of the pitot system and wiring from the front of the plane, so they are deferred until after the mating of those halves. On the other hand, the box is in its place, so it needed to be documented. There is one pneumatic tube that you see connected: the static system is confined to the tail cone, so that went together already.