Operational lifespan of 60's and 70's trucks

Modern vehicles are far more durable. When Leyland was testing the water with the Gas Turbine, they were touting an engine life of 400,000 miles, IIRC; modern engines last double that distance, and more. 20th Century cabs would be full of rust after 5 years; 2010-model trucks look like new on the road today.

Of course, the modern vehicles cannot be repaired as easily. The crap that kills them- control systems mainly, are foisted upon us by legislation. The motor industry loves it, because it means they can sell the extra hardware, and keep selling it. The banks love it, because they know what design engineers are up to- preparing for the next round of emissions/safety/security nonsense. They don’t want maverick firms putting others out of business, with clever ideas. Those ■■■■■■■■ like their 10% guaranteed.

The technology exists to make vehicles which last 20 years then, with an ordinary overhaul, do the same again.