Gray Marine, of course.
Scary.
Lucky for me the safety shut down devices (which I *think* are something like spring loaded plates which are rigged to close when the incoming air velocity exceeds certain amounts) did work.
It was screaming there for a while...I thought it was going to blow up.
Years later I was offered a pair of those type of engines, complete with crash boxes but declined the offer.
Now if they had been 471's (which can be good for 30-35ft boats) or 271's which can be good light-plant engines...or 353's which are used in a lot of seine skiffs, or almost anything other than those 671's which at one time were very common on the West coast, then it would have been worth it to take possession.
I’ve seen youtube videos of Diesels “running away” and it is some scarry stuff.