This will not be of much help, but interior pieces of trim often have a lot of holes in them since they need to be screwed down. The trim could have been wood or stainless but it would have had the screws in the same place. This is a general sort of thing; the hand natured of some Mercedes back then does not make this a hard and fast rule.

The pieces of trim with few or no holes are normally found on the exterior where a cleaner look was desired. If screw holes are in such a piece of trim it would be mounted someplace where the screws would not normally show.