Yeah, that's certainly not good. I suppose it depends on how badly it overheated as to the extent of the damage.
If you haven't already, I would suggest posting on a good Duramax forum to see what guys in the know have to say about it. I certainly understand what you're saying in cost to repair, but since you bought the truck new and it is still in good condition it may be worth fixing it. That era GM Duramax are typically pretty durable. My gut tells me it's probably just a head gasket but I get that the costs add up quickly when checking/machining heads, etc.
Best of luck and please let us know how you make out.
