To further clarify, the 123 Benzs were produced from 1978 to 1985. They are the older style sedans and wagons.

The aspirated MB diesels were not designed for the turbo and do not include components specific for a turbo configuration, so an aspirated MB diesel would not be one to consider adding a turbo. The OM617 all iron 5 cylinder w/turbo would be a better choice, but an even better choice for performance upgrade would be the OM603 that was available for the 124 and 126 model Benzs offered after 1986 in the US, but these cars were available in Europe a few years earlier.

The 190D, a 201 car, had I think a 4 cylinder diesel in 1984 and 85 I think, but later used a OM602 aluminum head iron block 5 cylinder. Someone else here may know well more than I about the 201 cars.