KC 135 - B 707
Seems to be that some believe the B707 and the KC135 are one and the same. They both share the same genesis, the Boeing 367-80. The KC135 pre-dates the B707 by about 18 months, is a narrower and shorter airframe with different construction.
Apart from training flights the aircraft would have been predominately subjected to heavy weight take-offs and over time has been given significant engine upgrades. The type first entered service in around 1957, fifty-six years ago. The last production airframe was built in 1965 so the accident aircraft was at least
forty-eight years old.
Hopefully the cause will be determined and published, otherwise we learn nothing.