That's the drives like a space hopper car we were talking about above.
Some interesting things I took from that video:
The mechanic clearly takes the head off lots of these engines, and from experience he expected this engine to look like a coal mine inside. That isn't experience of other engines, experience of VAG diesels. So why wasn't this one? There are two stand out features of the car history:
Very regular cross country runs (hence the high mileage).
The engine was "chipped" which gave it better economy.
So it has the ideal usage for a diesel, not the shopping trips and school runs that most get, and it has been remapped to inject less diesel. Both would help keep the carbon deposits down.
It is also an ancient design with almost nothing to go wrong: mechanical pumps, single point injecton, 8 valves, only one cam and I expect that isn't a variable geometry turbo. I wouldn't expect a modern diesel to last as long as that old tractor engine.
I suspect given the turbo is in good condition and the cam looked in pretty good nick that the engine has never been above 2000 rpm.
Edit: Oh, and I notice he was still climbing out of the passenger side door