My ft tag bracket was taken off my car when I purchased the car in 1976 or so (Alabama only requires rear tag), but it still has the plastic inserts, original screws, and even the rubber bumper in it, as well as pretty heavy paint. I could not see any AAC or any other stamping in it, but maybe if it were stripped I could? Attached is a photo of one of the screws and the plastic insert.
I also checked my Rear tag bracket (never removed from the car and even with the original seller's tag surround - Joe V Clayton- Arab AL). No AAc on the rear tag bracket (that I could see), but there was a GM pn 3913608 on the backside. The tag attachment screws appear the same as the ones in front bracket. photos attached.