Well, the Buffalo, YC-14, YC-15 each have relevance, as does the C-17! However India Four Two is the only one to get it exactly right.
QSRA (Quiet STOL Research Aircraft) was one of the Buffalo prototypes modified by Boeing with a new wing, Lycoming LF502 turbofans (leftovers from the Canadair Challenger development program, in fact) and all new flight control system.
The QSRA proved the Upper Surface Blown (USB) aerodynamic concepts which enabled the Boeing YC-14, which lost out to McDD with the YC-15 in the competition for the C-17 airlifter. Of course, Boeing won out in the end when they later bought McDD for peanuts - the C-17 contract was the best asset on the books!
The QSRA was a contemporary of the deHavilland designed, RR Pegasus engined augmentor wing research aircraft which, while arguably more efficient from an aero perspective, was anything but quiet as a prototype (think, two Harriers in formation)!!
Over to you India Four Two, you have the wheel.