Ya, it's a B3. I've always wondered why it doesn't look like the B3 has a traditional prop hub. In smaller boats I recall there being a rubber hub that would act like a shear pin and fail before this type of problem occurs. In mine it looks like straight SS. Maybe there's too much HP and torque? Without it, I can see how the gears in the drive take the beating.
My mechanic is a certified Merc. mechanic and very good. We tore the drive completely apart and did with the precision of someone who's done it 1,000 times. However, personally, I'm leaning towards complete drive replacement, but I'll have to see where the numbers fall.