Yanmar Engine
My best guess is that at 16HP, it is the replacement for the old 2Qm15....
I had one in my last boat from 1979 to 2006, and to my knowledge the next owner is still very happy with it.....Pretty much bullet proof.....easy to maintain.....with one small exception it was really trouble free.....
If there are any specifics you want, and I can answer.....just get back...
Regards