We had an 86 S10 with about 350k, it wouldn't have made it to 500k, at least not without some 'plastic surgery". It had the cancer real bad. Guy my mom sold it to pulled the bed and built a wooden stake bed.
My brother in law's 99 GMC Sierra has almost 300k. Still original engine, rebuilt tranny. He got it from a guy I work with for $100. It was believed that the engine was toast, but it just needed plugs, wires, ignition coil, fuel filter, TPS, and an exhaust manifold gasket. It went from sounding like it was about to die to running like a champ, all for under $500. 4.3 v6.
My 85 Nissan truck is about on it's last legs. Needs a tranny and at the very least a new head gasket, but possibly a rebuild on the engine. It's had a rough life though and held up amazingly well. it's at 252k.
The XJ is only at 163k, but just passed emissions with numbers to rival my CA emissions equipped 94 Geo Tracker with its 1.6l 4 cylinder when it was about half the age of my XJ.