Yes, this is exterior. Sorry to not clarify.
It is black in colour and looks like a continuation of the rear gate window.

Any help would be appreciated.

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83 300TD (need rear wiper assembly dead or alive)
84 300SD Daily driver
85 300TD almost 400k miles and driven daily.
98 E300D *sold
86 300SDL *sold and made flawless 10 hour journey to new home.