Israel Aerospace Industries unveiled a new tanker modification this week: a boom-equipped tanker based on the Boeing 767-300ER, with a new fly-by-wire boom.
What's interesting is that Boeing, back in 2005, firmly announced that it couldn't be done. In a briefing at the Avalon air show in Australia, I asked why Boeing wasn't proposing tankers based on used 767s -- and low-time 767s were widely available on the market at the time.
The answer was that you needed the high-gross-weight ER version of the 767 for a tanker mission, but the great majority of the HGW airframes were -300s, and the longer-body aircraft did not have sufficient tail clearance at rotation to accommodate a boom.
IAI has solved the problem (patent here) by designing a low-profile boom and providing a structural recess for the pivot mechanism. It all seems a little obvious in retrospect.