7zap has been pretty good in terms of part numbers.
https://audi.7zap.com/en/usa/audi+4000/a40/1982-3/1/105-4000/There is a specific bolt and washer for the CY engine listed and I have no clue if thats whats in the car now. I doubt it. There are a few specific pulley pieces based upon the engine code and if it has power steering (mine does). Oddly enough there is a different water pump pulley listed (on a different diagram), which I believe I do have.
This thing is wild. I'm thankful to have a vw diesel guy here that helps with that sort of stuff, but since this is such an odd car its been fun.