The old five cylinder deisels are almost indestructible.
It's worth pointing out that the 190D had a different 5 cylinder engine than the 300D. Take a look at the stickies on this board, but the 190D 2.5 5 cylinder is a OM602 2.5l aluminum-head engine. It's not a bad engine, but it's not as indestructible as the OM617 found in the '85 and older 300D (and 300TD and 300SD). Especially if it still has the original cylinder head, you have to be VERY careful to keep from overheating it. However, as long as she doesn't overheat, she's good to go.
Also, AFAIK, the "modern" 190D started production in 1984, and all diesel 190D's sold in the U.S. were W201 chassis cars...by the time they switched to the W202 chassis (around the same time they started calling them the C-class), they had dropped the diesel models. There WAS a 190D (which had a 1.9l engine, heaven forbid
) with two different bodystyles, sold between 1959 and 1965...but, that's a completely different animal from the 190D's sold in the '80's (which had either a 2.2l OM601 4-banger or a 2.5l OM602 5-cylinder aluminum-head engine).
Hope it helps...
As they said, there's nothing more expensive than a cheap M-B. The engines'll run forever if they were maintained reasonably well, but there are other considerations. I retired my first M-B because of a worn front suspension, and my second is going to be going that route sooner rather than later, and for the same reason...