Sure sounds like the coolant hose blew, lost your coolant water, didn't notice the engine temp gauge raise to extreme, perhaps didn't hear or realize the engine fan kick in hard, and then cooked the engine?
Maybe the coolant hose had rotted as it was likely 12 years old and finally split letting water under pressure blow out over time but the low coolant level should have thrown a code on the DIC alerting you.
Diesels create a lot of heat and without nearly enough coolant running thru the engine, It only takes a couple minutes before it ruins the engine.
If the engine can be repaired and the truck is otherwise in good condition the best choice may be to have it fixed as the resale value as you found out is much higher on diesel trucks than you probably thought. Only you knows the truck and what actual condition it's in.
Fixed, you can then choose to keep it or sell/trade it in on a different/newer truck and easily recoup most or all plus of the cost to repair it or replace the engine. A truck with a blown not running engine doesn't have much value at all in the market place! Truck and drive line and a repairable Duramax engine shouldn't be worn out at 374,000K or about 230,000 miles. It's ultimately going to cost you money no matter which decision you make! Best of luck to you!
