Good input guys. There still has to be a driveshaft along the wing (in the present 609/Osprey a/c) because as stated, the loss of one engine still allows the good engine to turn the affected/relative proprotor on the other side of the machine. In my messed up mind....take a Chinook a/c and fly it sideways??? Engines in the "middle"...resultant lift at either end. I am speaking specifically about engine and drivetrain in this example.