Ten years ago Boeing won the contract for 180 new air refueling tankers. They have not yet finished delivery on all the planes. Boeing says they have lost $5 billion on this job. There was a hassle over how to wire the aircraft, the Air Force thought they knew more about aircraft wiring than Boeing did. Then there is the rear view TV system. They wanted to seat the boom operator up in the cockpit rather than back in the tail. So they put in a TV system to let the boom operator see to steer the boom into the fuel receptical of the refueling aircraft. The Air Force has complained that the TV system image is not as good as the image you get looking out thru a plain old window. Air Force has been "witholding" $12 million per plane. Boeing has promised an improved TV system, some time in the future.
180 new tankers aparently isn't enough. So, USAF is going thru the whole bidding process, pitting Boeing against Airbus all over again. New specs, new contract, and if Airbus wins, they will furnish their own tanker, based on an Airbus airliner. Speaking as an old USAF maintenance officer, I would much rather have a larger fleet of the same aircraft, than a mixed fleet of half Boeing, half Airbus. The mixed fleet means I have to train my guys on both aircraft and I have to stock different spare parts for both aircraft.