Same chassis, some body mounts, same axles, same engines and gearboxs.
Depending which deisel you have they will be very similar with the ir cloths off, most of the wiring goes with the body as do the brake lines.
A big differnece is the ABS system employed (if fitted) you will be best keeping the one that goes with the body.
You may find the fuel tank is different but both types fit the same chassis, all asuming they are similar age of course, there are subtle differences between 200 and 300 models, but still the body mounts are the same.