Inspired by the discussion on What are the two very large "blue" cylinders attaching to the combustion chamber of each Rutherford Engine? and especially jkavalik's excellent picture of the Merlin engine:
Does the entire Merlin gimbal? On the SSME, the low pressure turbopumps were mounted to the vehicle structure, with flex hoses between them and the high pressure pumps. Only the thrust chamber/nozzle/high pressure pump assembly gimbaled. I can't tell where the interface is on the SpaceX vehicle from this picture.