318 exhaust manifold help.

This chart only goes to 1973, but perhaps it's one of these.

http://www.moparsunlimited.net/mopar_exhaust_manifold_casting_n.htm

Left one - 2465769 - 1967/68 Dart & Barracuda, 273 - 318
Right one - 2465847 - 1964-66 Dart & Barracuda, 273