Road Runner Nest

Every once in awhile I see the 6 button pattern, '73 style bucket seats, in a '72 car. Does anyone know if this was a running change during production? Or were both patterns available at the same time? I guess I've only noticed this on bucket seats. I wonder if the bench seats also changed during the year?

late in the year models sometimes had the next year options put in, if they ran out of stock on those things.