I have owned 4-67 Dart GTS 383 cars with the 17" unsilenced air cleaner and currently have one with the AFB base AND the AVS base. The AVS base came off of a 68 Charger with a 440. I have helped restore one 67 440 GTX 4-speed and the original owner still had the air cleaner, which was the 17" unsilensed. I have also helped restore a couple 67 440 GTX's with automatics and they had the dual snorkel air cleaners, so my guess is that Daryl is right...