The first one, and MD2B packed it in after 10 years of my use. That included 2 trips up and down the east coast, so it didn't owe me a thing. I found an MDIIC locally, and installed that and ran it for several years before selling the boat. They're good reliable slow turning engines. Slow starters(no glow plugs), if you needed a part, they cost a fortune. But they did cause quite a rumble below in noise and vibration compared to a larger 4 cylinder I found later. The newer engines have lots of improvements, even in the smaller engines.

The biggest offender I've ever spent time with was a friends 1 cylinder Farymen. How that thing did thump! Just a newer version of the old fishing make or break engines from the turn of the century.