My guess would be original '68 seats with headrests. I think in the research-facts area of this site shows the differences. Yes, PHS would tell you for certain if the car came with them. Not many '68's came with them, so would be a cool option to have.
+2
I think they only produced 2000-6000 in 68. Very rare. The parchment color for the 69 would be different than the 68. PHS will prove it. There are stamped nos on the seat frame at the top. Take the head rest off and back cover. There will be a date code on heat rest and frame and possibly a part no.
I picked up a 68 pair with new vinyl for $150 /pair. Sometimes you get lucky!