IMO, the best comment I've seen in this thread is; The dealer is using after market props rather than original Quicksilver merc prop. Just bring the original to Tim at Performance Propeller and have it rebuilt. fyi, I don't see where there is an after market lower unit for the 4 stroke 60. Only 75 hp and up so, It is most likely a Merc replacement gearcase. All trackers have the engines mounted the same height at the factory. Make sure you don't have a transducer or something causing air turbulence at the prop.