I'm new to boating. I recently purchased a 1991 Four Winns freedom 190 with a 4.3L and OMC cobra outdrive. The boat is clean and solid. I found some water in the oil when I drained the outdrive. I do have a good local mechanic who looked at the outdrive for me. The prop shaft is bent and worse the shaft moves radially 10-12 mils. I'm guessing the prop was bent and the imbalance produced roller bearing wear over time. I'm guessing lots of hours on the motor and outdrive. He indicated that he doesn't hear noise in the upper gearbox. Should I consider repair (I'm guessing a complete rebuild) of the lower unit or should I look at conversion to Merc or Volvo outdrive? How much will the conversion cost? Can I buy a transom mount that will allow the Merc or Volve to bolt to the 1991 4.3L? Where can I buy the conversion parts?