Back gasket 196.0201 - material, dimensions and/or part number?

I have just got a 196.0201 from 1982 which i opened up to replace the battery. The back gasket is made of a red material, which makes me believe that it may be a plastic gasket and not one made from rubber. The gasket may also just be an older rubber gasket and therefore feel like plastic... I have however not been able to find the original part number for this gasket online to confirm its intended size and material. Any help finding the part number or information on the original material would be appreciated.
I went on the cousins uk homepage where they seemed to have listed a bunch of the case parts in a pdf, that however showed the watch having chrono pushers and some other parts which this model definitely does not have, therefore I'm very skeptical of that information.

Here is the image, it corrupted somehow in the first upload.

It sais pusher, not chrono pusher. Your have a pusher for the date? The back gasket should be X13342 at Cousins. AFIAK, hard gaskets like this should be replaced every time you open the back.