Mike, yearone sell exhaust manifolds with air holes.As amatter of fact it is hard to find exhaust manifolds without the aie holes unless they are used ones. Have not found a company that has non air hole manifolds. BILL
This may not be accurate, but I thought that generally all big block manifolds after '65 were drilled for a.i.r., and had bolts screwed in place when the pump was not present. Only the '65s were undrilled.
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