The four-speed manual 240D is prized and considered a big upside over the automatic, which owners describe as 'eternal' in its slowness. The Euro five-speed (never sold on a US W123) is coveted and sometimes swapped into turbo cars to make them capable highway cruisers, though clean originals are considered too nice to modify.
Manual four-/five-speed versus the automatic
Mercedes-Benz W123 · driving