1965 273 4-bbl intake. What is this connector for?

The oddest thing is that the casting around it on the inside looks like it is an after thought on the casting.


Tapped power brake port from inside the runner
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Underside of the "shared" port to nowhere
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Casting number of the 67 CAP 4bbl manifold
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Visable power brake tapped port and undrilled or tapped "shared" port to no where
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