My Sport would have become a "parts bike" long, long ago if not for the members of this forum.
I tried, once more, to have my local parts store bring up a "throttle linkage socket" for either Volvo or Mercedes.
No go. At least here, in the US, don't expect to find this part easily on the fly.
If yours is showing signs of loosening, or cracking - time for pre-emptive replacement.
I'm inclined toward the all metal (Mercedes) part. Once installed - plan on a throttle body balance . . .