Are these 340 exhaust manifolds
pass - 3418623 This is definitely a 71 340 Manifold.
driver - 3614368-1 This one is a 72-73 manifold. A 71 Manifold would be a cast # 2863553 IIRC Same as teh 68-70 340 manifolds. According to my books it's a 340, Tony's Parts sells them with the above manifold as 71-73 340 manifolds. I don't have a 72-73 parts book to confirm application.