I'm looking at a nice little fishing boat/cruiser with a Detroit 353,
only about 1000 hours on it, runs great. I know this is one of the
more reliable diesels ever made, but I have heard some not-so-good
things about the ones that came with aluminum blocks. The boat was
built in 1987, so the engine is at least that old. The owner doesn't
know much about it.

Is there a way to tell which version it is?

Thanks,

Bob