A marine propulsion device is provided wherein a flexible bellows (33) surrounding the universal joint (20) disposed between a marine engine (5) and a stern drive unit (2) is mounted to rotate with the universal joint itself. The universal joint is disposed within a chamber (61) delineated by the bellows itself and by end caps (34,43) mounted to the universal joint shafts (25,30). Supports (53,56) for the universal joint bearings (54) are constructed to permit free flow of fluid around the bearings. A quantity of lubricating oil is supplied to the chamber and at least partially fills the chamber when the latter is at rest. Upon driving rotation of the device, the bellows and universal joint and lubricating oil all rotate together. The resultant centrifugal force causes the oil to flow radially outwardly through the bearing supports to lubricate the bearings, with the oil forming a rotating mass engaging the inner bellows face. To support the bellows against the rotating mass, a helical spring (69) is mounted externally of the bellows and within the bellows convolutions, with the spring being anchored (73) adjacent both ends of the bellows. In addition, the bellows function as a finned heat radiator.