66 Dart Headliner Question

Im getting ready to install my headliner on my 66 dart 2 door hardtop. I have a set of bows that has 5 bows. Im reading some for sale ads and I see there have been sets with 5 and sets with 6. Why the difference? the headliner I bought has 6 seams for 6 bars and the car has 6 slots also but I only took out 5 when i tore the old headliner out. Anyone else ever change the headliner on a 66 2 dr hardtop and have pics or can add any helpful suggestions or comments? I welcome any help I can get.
Thanks Rod