64-66 cuda fold down seat into 63-66 dart
The folding back is much narrower and probably lower than a standard seat back — it would expose a lot of metal on either side. It is also thicker so it may not actually clear the package shelf, and, of course, requires the hinge parts. The seat base may not be a direct replacement, since the Barracuda seat has to bolt down, while Dart rear seat bases are merely hooked. I say this because I have a 67 fastback and a 67 Barracuda convertible, and the back seats are completely different and not interchangeable.