I also must admitt that I love those old w123 or 124 300TD 5cyl diesel turbo motors... they're just great; although a little noisy at idle and less powerful than the japanese engines, these engines would run forever... very robust simple engines.
My prof at Uni drives a 300D... he has put 700000km on it now, but it was starting to lack power, so we tore the engine apart- to my amazement, the horning marks were still there. But the cam was almost round. So we put in new rings, bearing, and a new cam in. And also flowed the injector and serviced the pump, now the engine is running like a champ again.