Left side 340 HP exhuast manifold and late 71 340 intake manifold

The cast date is usually a month or two before car was built.
The 71 cars were finished being built by sometime in July as I recall. I was
buying new Mopars by then.
The collectors on this site can explain better on the date codes = I am a Racer!
If the manifolds were cast in July to Oct = They would be on a 72 car and probably
a 918 or 025 number