Alternatively why would the USAF take a UK-based frontline KC-135 and instrument it and then de-instrument it rather than use a KC already destined to be gutted and modified at the same location that is undertaking all the trials and instrumentation activity?
Still, knowing the procurement world anything could happen but the KCs destined for RJ conversion are not from the desert, they have come directly from the in-use USAF tanker fleet.