A flexible coupling includes a flexible diaphragm body having a first end and a second end. A member is fixed to the first end of the flexible diaphragm body. A splined member is fixed to the second end of the flexible diaphragm body. The splined member is configured to shift relative to a rotatable member rotatably fixed thereto in response to axial displacement of rotatable members interconnected by the flexible coupling. The ratio of inner diameter to the outer diameter is selected to allow for packaging the flexible coupling in a confined space.