The ones with the blue borders were indeed inserts in packs.
The ones with the black backgrounds however, didn't come in packs, instead were the prize for sending in yards from the game cards.
Here's an ebay listing for the game cards. On the back you can read how to go and claim the send-in glossies.
http://www.ebay.com/itm/1984-Topps-I...QAAOSwd0BV3Ljo