I bought an aftermarket exhaust manifold for my 88 5.8W that is a little different than the original. It has holes above each outlet for I believe some kind of emmissions equipment. Any way since the old one doesn't have that equipment I need to plug those holes. The vendor told me to use pipe thread plugs. Every auto parts store I checked said they are not allowed to sell plugs that might be used to modify the emissions equipment. Can someone tell me what size of plug I would need for this. There must be a measurement from somewhere.
Any help would be appreciated.

Thanks,
Ron

 

they are for air injection, I think only the newer models had it like that. just take the manifold down to a hardware store, its probably just a standard pipe thread.