Cessna designed the 180 for a 225 hp O-470-A/-J engine. The design of the engine mount was revised TWICE within the first year of production. First at SN 30527, and then again at SN 30640. In June 1954, a bolt on kit in a attempt to strengthen the mount on older aircraft. By September 1955, a standard repair was added to all the mounts to again strengthen the mount. Ultimately, Cessna abandoned the original design in February 1956 and issued SL180-1 allowing owners of the O-470-A/-J powered aircraft to install the new 0751001-1 O-470-K engine mount. By 1956 there were 4 versions of the original 0751000 engine mount. In 1956, Cessna claims that the engine mount design change from the original engine mount to the 0751001-1 engine mount reduced approximately 95% of the engine vibration.
The Aircraft on the Right has a 3rd generation 0751000 Engine mount. It lacks the last set of reinforcements added prior to the introduction of the O-470-K.