92 Cougar head question

I am repairing my daughters Cougar. Blown head gaskets cracked heads etc. I purchased some nice rebuilt heads from a dealer on Ebay. The heads are
the same except for a small hole that connects the exaust to the intake. The hole is in the intake manifold surface with one on each end of the head. My intake manafold does not have a match for the hole. Does any one know what this is? What year intake would I have to swap to get a match? Are these really Mustang heads maybe?
Thanks new2cougars
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