Date code on stock exhaust manifold

If you can not read the date code on the original, there is no way to know what was on it.

'Build' dates were not recorded back then, only the day they hypothetically 'hoped' to start the cars build. That is what is on the fender tag.

Small blocks have a final engine assembly date on the front face below the drivers side head, so whatever the date on the manifold was, it should have predated that date for sure.