I’ll have to say my 1987 E350 Ford van with the 460 bought new and has 49,890 miles. Replaced the intake gaskets back 17 years ago, removed engine to replace some freeze plugs, removed the pumps and egr tubes at the same time. Rebuilt carb 3 months ago (sat for two years without starting) runs great and never saw any coke. Changed oil after 12 years, 9-10 mpg but it’s payed for itself a long time ago so I’m ahead of the game big time. Still has same trans fluid, rear fluid and brakes, I did change water pump a few years back. Hardest thing was finding the matching belts. Just put 6 new tires on, 23 years on that set, still great tread but dry rotted.