I would be very careful of the rebuilds you see in Boats and Harbors. I read some real horror stories when I had my subscription to Boatdiesel.com.(a good source to compare engines and read about issues and fixes) I am sure there are dealers with good reputations too. Cheap usually means rebuild and the definition of rebuild varies depending on who rebuilt it. Having said all of this I would spend the extra money and buy a factory reconditioned engine because you know every part was checked to factory standards and is either new or a rebuilt part.