I found a Broadcast sheet in the springs of the back seat in my 69 Camaro..

That's interesting.

Fisher Body built the bodies, including all interior soft trim and seats. The completed bodies were then transferred to Chevrolet final assembly, at which time the last six digits of the VIN was assigned. They were queued in the body bank and released to assembly based on labor content. Body and Chassis Broadcast Copies were printed by Chevrolet when the completed body assembly was released to the line.

For a BBC or CBC to be stuck in the rear seat springs, someone in Chevrolet final assembly would, for no reason, have to remove the rear seating and place it there.

Like to see what you have.