I would question Pelican Parts about the one below to see if it fits your year and model.
If My Notes are correct the Mercedes part number for My W123 is 1236700239 Rear Windshield seal .
The below Lemfoerder Window seals part number is 123-670-02-39-INT Shown as $57.50
Pelican Parts - Product Information: 123-670-02-39-INT
The Precision