Well I was given an 83 Troy Built "Horse" model. Its 7hp and the motor smokes. I'm considering putting a new motor on it and doing tilling in the spring. I've never done tilling commercially. But it could be a nice $$$ adder in april when I'm not doing anything else. I "don't" do raking or spring cleanups. Its a rear tine model. Can the vibration get tiring after doing it all day?