Life of a 12v92 Marine App.

I'm looking at a 62 foot sport fisher, with Detroit 12v92 Turbos 1050 HP. each I have no experience the DD Motors, and have no clue what the life might be, these engines have 1900 hours on them currently and they seem to run great, I did read one article that stated it's not uncommon to see a rebuild at 2000 hours, I'v talked to several commercial fishing guys that said they got 10k out of there's but there running everyday at low speeds. Is there any thing I can Listen or look for as there running ?

if only an engine could tell you it's life expectancy by listening to it. But yes, your ear is a great way to hear any changes.

You are correct about load factor determining lifespan. That is so true that the major diesel manufacturers do not plan for rebuild based on hours or mileage anymore. They base overhaul planning on total fuel consumed.
e.g. Rebearing and reseal @ XXX gallons of fuel.

You also want to keep accurate track of oil consumed vs. fuel consumed. Any increase in oil vs. fuel will be valuable info. I'll guarantee Detroit has published data for acceptable oil consumption as a % of fuel burned.

You might get that data from a Detroit Marine dealer. Or, what you can do is begin an oil sampling program.
Any trends in increased ppm of wear metals will be a pretty decent way to see what if anything is wearing out.

Sampling along with cutting all oil filters and looking in the pleats will lead to very few surprises. You'll know when rebuild time is coming.