Bosch number for late 308/328 wiper arms?

When I got home yesterday, the molded plastic cap that conceals the securing nut on my left wiper was gone. Looks like the plastic cracked, probably when I lifted the wiper to clean the windshield, and flew away while driving. The 308 wiper arms shown in the SPM image don't appear to have the cap but the '85 328 unit looks right. I'm hoping its a FIAT or Mercedes part.

Funny how much it stand out now like a black eye.

 

I couldn't find wiper arms in the cross-reference arms don't appear in the cross-reference threads; no luck anywhere else either.