Attached is information in regard to Outside Rear View Mirrors from 3 different sources ; first is the text from the "1965 Only" MPC (no illustrations are included in this MPC) ; next is the text section from the 1960-68 MPC , and a page from the 1960-68 Illustrations section (including some text also) ; finally, is information from the text section of the 1965-72 MPC, consisting of one page of text, and one page of illustrations. There are no additional illustrations in the Illustrations section of the 1965-72 MPC.
One thing to be aware of, especially if looking for a mirror as Chris pictured in the first post (the conical B5AZ-17696-A), is that, prior to 1964, this identical part number was used for an entirely different appearing outside mirror. Prior to 1964, the B5AZ-17696-A mirror was used for one that had been used since 1955 (as one might surmise by the "B5" part number), which had a similar base with the "FoMoCo oval", but had a round stainless steel replaceable head which threaded onto the base, as opposed to the conical head which was held onto the base with a post and a set screw. I have attached pictures of both. The earliest of the B5 mirrors actually had a different part number, but in the early 60's was changed to the B5AZ-17696-A.
One final thing worth mentioning ; all of the items from the MPC's shown are "Service Parts", which may, or may not be the same as Factory Parts. However, since all outside rear view mirrors until 1967 were "optional" or Dealer Accessories, and even if ordered with the car from the Factory, were shipped loose (except for the 1965-66 Remote Control Driver's side mirror) with the car for the Dealer to install (someone correct me if I am wrong on this). This would then give the Dealer the opportunity to sell the Customer a different "higher priced" rear view mirror that was available at the time, which would account for seeing so many different outside rear view mirrors on Mustangs, as well as on other models.
Personally, I have always associated the C1SZ-17696-B Rear View Mirror (Type 2 shown in the 1965-72 Text illustrations section, and Type 3 shown in the 1960-68 Illustrations section) as the "standard" Optional mirror on 1964-1/2-1966 Mustangs, probably because that is what was usually pictured in the sales brochures when the cars were shown with Outside Rear View Mirrors (see picture from 1964-1/2 Sales Brochure attached).
Hope this helps.
Bob