From the Delco ETR 2000 Series radio manual that came with your shiny new General Motors vehicle in 1986. The FM Stereo listing was from the FM Atlas, while the AM Stereo listing was maybe supplied by Motorola? A lot of the stations have a * next to them, but it doesn't indicate what that means. I also noticed a brief mention (on page 13) that their radios would also receive the Harris AM Stereo system, which by then had switched their pilot tone to 25 Hz to make it compatible with C-Quam receivers.
drive.google.com
delco_1986_ocr.pdf
drive.google.com