A number of people have replaced the
SD50 with SD 60. There is an adapter plate available from
Yanmar. The early SD 60s had problems of their own, subsequently fixed. Last I heard the SD 60 was about $7000 in
Maryland for the unit + adapter +labor. I was tempted to swap our SD50s out but then I learned how to lap the cones, and so for 4 hrs of my labor once every couple of seasons I saved a lot of
money. The cost really starts to rocket when
service providers start spinning stories about having to remove the drive take it to the workshop, blah blah blah, so then your
boat is sitting
on the hard with a hole it it, at the mercy of the shop, so you pay for the
haul out, the yard space, and any other costs like rental cars, airfares or motels and so on. So I would want to make pretty sure the drive is a write-off and not just a worn
clutch cone or maybe a damaged
gear set.
Start with the top of the unit while
boat is still in the
water, can check the
clutch, shafts, and top gears and bearings. IF that shows no damage you will need to get hauled to inspect the lower
gear housing at the prop, prop and lower shaft and gear set is easily removed and inspected. If still a problem inside the leg, that is when it may need to come off and then the clock will start running expensively.
Oh before all that check that something has not wrapped itself around the prop like a cable or chain on a fish/crab trap, this will cause the
engine to stall.