273 / 318 Exhaust Manifold Question

George Jets said
Look at the sweeping flow of your Commando manifold, looks like a Stock 340 performance manifold.

Then look at this standard A Body manifold on this 72 Duster 318, it is not the 340 manifold, just the standard manifold.

The shape and the way your's kicks out looks like it will deliver more performance. So Yeah, you do have some nice Commando manifolds On there.

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View attachment 1715917321

Any chance you have a better picture of what your passenger side exhaust manifold looks like?

The 340 (68' - 71') output to tail pipe is larger, flat and no cone, the sweeps are similar. A guess is the openings at the head may also be larger on the early 340's. If I were to use the best cast iron exhaust instead of headers, I would buy the after market ones for the early 340, around $600.00. Don't forget the special bolts and cone washers to go with them.