Sure looks to me that those parts are coated with yellow Alodine. I'm pretty sure Jim Ridge is applying yellow Alodine during alternator restorations.

About 10 years ago I sent Jim Ridge my double pulley alternator for restoration. Jim advised the case had been sandblasted by a rebuilder, was unsuitable for restoration, and he would need to find another that had not been blasted. He found another good case, and he took the photo below with double pulley in his shop at completion. Note the case finish with double pulley is without Alodine.

Later I realized my alternator should have had a single pulley, so I returned it to him to switch the pulleys. He told me that he had only recently learned Chrysler alternator cases had a finish different than the one he had previously put on my alternator. He said he would put the new finish on my alternator along with the new single pulley. The new finish is shown in the photo taken by me of the exact same alternator with single pulley. Unfortunately the lighting is not the same as Jim's photo, but I strongly believe that he had applied yellow Alodine. Note the hint of rainbow appearance.

Alodine is sold two ways, as a clear solution without dye, and also with a yellow dye added. In my experience, the yellow Alodine eventually dissipates in an engine compartment environment, but is easily renewed in place with a new brushed-on coating.