Since that's a 68 Barracuda and if you want to be correct...use 68-69 B body seats. The 66-67 will work, they just have a hard shell back and a little chrome trim strip. The rails however are a-body unique, ones from a 67 Barracuda (or Dart) WILL work as well. Just need to swap them. Regrettably no one (that I found) has reproduction bucket seat rails for the 67-69 a bodies. If you DO go from a bench to a bucket, don't forget to reinforce the seat mount points on the floorboards. If you just drill holes in the floor I suspect you MAY end up tearing the sheet metal over time. The factory reinforced that area.