Yes, and the bracket system is not for that particular speaker you have. With GM vehicles you had to have their speaker to fit into their bracket, and back in the 70s or 80s there were no affordable speaker replacements or upgrades that fit. Nowadays you can order an exact replacement that will fit the original brackets, and you can buy used brackets here in the forum parts section and/or eBay, if you wanted to restore to original. The part of the bracket that holds the back of the radio is just for the stock radio, and the part of the bracket that holds the speaker is just for the stock speaker.
https://67-72chevytrucks.com/vboard/...d.php?t=735298