68 vs 69 Barracuda Seat Interchange Question.

My 68 Fastback came with and still has its original bench seat with fold down arm rest in the center but no head rests. Feeling across the top of the seat I can't feel any revision areas to install them so I assume I would need to replace the seat to add the headrest option. Is this true?

Would 69 bucket or bench fit this 68. I've had both a 68 and 69 Fastback and it would seem the 69 interior room is larger. Could be my imagination.

Thanks !!