Found this on the net.
Boeing-Bell XV-16A PLR VTOLby *
BisproContrary to popular belief, The V-22
Osprey is not the first joint effort by Bell and Boeing. In 1976, Boeing Vertol teamed up with Bell's Helicopter Division on a proposal for the Army's PLR (Power Lift Rotorcraft) program.
Designated XV-16A in the VTOL series, this clean-looking and able performer combined Boeing's experience with transport helicopters and Bell's expertise in VTOL, in this case capitalizing on the tilt-duct research that culminated in the highly successful X-22A prototype a decade before.
The PLR program was canceled despite a successful two-year evaluation phase because it was found that its advantages did not outweigh the 35% increase in costs from operating it instead of a conventional
Chinook.