What you have there is the 150A alternator for the
V6 engine.
The items in your diagram don't show up for the D2, only for the C5 A6 V8. Checking the part number for the 150A A6 V8 alternator (038 903 018D), it cross references to the D2 V6, which normally has a 120A. The 150A version must have been fitted to the V6 as an option, and it seems someone has mistaken it for the 150A V8 version which is 038 903 018
G.
In theory then, the air guide for the 150A V6 D2 should work. That is 4D0 903 423B for item 20, and 4D0 903 655 for item 21 & 22 combined. I've got a couple of V6s at the workshop so I might have a look later if I get a chance
