I've found free electronic copies of some of the Sams Photofact Auto Radio Series! Search for "photofact" for the auto radio series: https://www.worldradiohistory.com/BOOKSHELF-ARH/Bookshelf_Sams.htm
Until clicking your link, I had not seen any Sams manuals since my high school electronics class. Thank you for the link to such a useful website.
The Sams Photofact Auto Radio Series manuals from approximately volumes 70-80 include 1970 and up Buick radios.
