[steely]

Rob,
am just seeing your replies - sounds like you found the cause I see (washer).
As for the item, it's 91110605501 for my '87. Sorry I don't know your PN. It is called the hub extension, or fan housing extension, or air diverter. There is another name that escapes me. These get fragile with age and the thin flange breaks off making them difficult to re-attach to the ALT. Might explain what happened to your original.

Maybe you can use my PN to see if you can find an earlier one for your 83, but they're dear - like $95. You might try getting one from a dis-assembler.

Do you have the parts catalog from Porsche (PET)? If you do a search here, I am sure you'll find a link to the Porsche site that offers them up as pdf files for free - very handy. The PET pdf is searchable - note that they call the alternator a generator, and the housing extension is shown with the housing (not the alternator) btw.

hth