are these very popular cars ? why are parts so hard to find for these ? compared to the 123 or 126 s ?

Lots of 190E cars still running around.

Problem with a 1984 190E is that they have many unique parts compared to later cars.

Even the 1985 has some significant changes, when they did a remake halfway through the model year.

For example, early W201 A/C uses a GM compressor.
Also used 14" flat faced wheels.

Unless this one is in immaculate, low mileage condition, you'd be better off looking for an 89 or up that has all the updates....

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles