70 Duster- Bench and bucket seat holes?

My 70 Duster is my first Duster project. I pulled the interior (bench seat), and it appears this car may have been drilled for bench and buckets. Did they all come that way? Makes sense I guess. The hole layout and drilling seems too good to have been done after the fact. There were no plugs in the unused holes though. According to the previous owner it was always a bench seat car.