comes with a new to me boat and had a big crack in the lower gear case. Its a 1989 20 hp Evinrude, manual start. I need to replace it. I have been looking to replace it with no success. Now I have to widen my search for other year model that would be compatible. Can anyone tell me what year to year are compatible with my outboard? Maybe not just the lower unit but the outboard itself. I'm thinking of buying same outboard for parts. Thanks!!!