The present invention includes a rotorcraft drive system comprising: an engine positioned at an end of a wing between a mid-wing spar and an aft-wing spar; a spindle positioned forward from the engine, the spindle capable of rotation between a hover and forward flight position, wherein the spindle rotates about a rotation bearing on an inboard split rib and an outboard tip rib or in a cantilevered spindle configuration supported by the inboard tip rib; and a tilt axis driveshaft connected to the engine, wherein the tilt axis drive shaft connects to a plurality of gears and shafts that transmit power from the engine to a proprotor gear box when the spindle is in: a forward position, a hover position, and during a transition between the forward position and the hover position without loss of power to the proprotor gear box.