Originally posted by ChristianRock Agreed, 5 million miles is crazy! How many engine changes does it go through to get to that point?
Older big truck engines would get rebuilt many times. They were designed to be rebuildable. New pistons, reconditioned crankshaft and rods, reconditioned cylinder head, etc.
That truck had a mechanical engine originally, a Cummins 350 Big Cam. The guy who owns it now replaced that engine at around 2,000,000 miles with an early Cummins Red Top (electronic fuel injection). It has likely been rebuilt at least once.