The only visual difference I can think of is the air cleaner assembly mounts. The 560 (117) is about 1 1/4 inch wider than the 420 (116). The air cleaner Assemblies are the same except the duel intakes on the 560. To make up the difference in the width of the engine they added a small bracket to the 420valve covers and the air cleaner is attached to that bracket. The 560 mounts screw into the valve cover and the air cleaner sits directly on top of the mount.
Hope this helps

Paul

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84 500 SEL (307,xxx miles)