My 2003 Chevy Silverado 2500HD D/A 4x4 EC/Sb has only 36k miles on it. I average about 3-4k per year, as we only use it for towing. It stays stored in the garage in the winter, has never seen salt, but has been rustproofed nonetheless. Maintained religiously, synthetic everything, and looks like it just left the showroom floor.
I bought this truck to order in 2002 and at my current age (33 yrs old) expect it to last the rest of my life as long as I continue to take care of it. I wouldn't trade it for a new one, ever. I'd never get an appropriate price for it given the condition. If anything, I'll do a dually conversion down the line if we decide to full time in it at some point.