Back then, Mercedes had a way of designing the bodies so that there was a very strong resemblance between models. In fact so similar, that it got them into trouble because the owners of the higher end cars wanted greater separation. So extra chrome and better quality interiors were added to the more expensive models. This is also true of the Ponton sedans and coupes.
The other thing I discovered is that just because it resembles each other, doesn't mean that they are the same part. In fact, usually not the same. You have to be careful. The EPC is useful mostly in that you can find the part number for each model and see if they match. Mercedes does substitute a lot, so not always reliable.
