help needed -exhaust manifold

I just purchased a set of Hermoff 6123 and 6124 manifolds for my 1994 Chevy truck. These manifolds have a hole for a AIR emission device which my truck
does not use. What do I use to plug these holes on my application? My local autoparts store where I purchased these items was unable to provide me with anything that would fit. Thanks for your help.
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Depending on what size holes they are a dealer should be able to aquire the correct size plugs. The smaller size can use a 1/4 inch pipe plug but it must be BRASS . They larger size I believe was 18mm;same size as the ever present oxygen sensor. There have been notes in the parts catalog giving correct pn's for the plugs. The dealer might jack you on the $ for the plugs because he didnt get the BIG $$$$$ for the manifolds
sr the former gm parts guy

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