Odd thought for a huge tilt-rotor aircraft, a MIL Mi-12 with just the transmission and proprotor moving for each nacelle.
This thought stemmed from the NASA Historical Monograph on the XV-15 which include a lot of back history on tilt-rotor aircraft. Platt-LePage Helicopters got into it looking at improvements that could be made to the Focke-Angleis twin-rotor concept with horizontally-spaced rotors rather than fore-and-aft spaced ones. Since the Mi-12 has this same configuration, it seemed a natural as a large tilt-rotor aircraft.