These are direct replacements for the brittle plastic OEM caps. These Bean Machine caps have the same footprints as the OEM Ford caps. Some aftermarket filters and caps cause the oil to bypass the filter causing unfiltered oil to enter the system, but not with the Bean Machine cap. Our caps still utilize the OEM and Racor filters. The O-ring is NOT included but comes in the OEM replacement filter pack. All caps are tapped with 1/8″ NPT for use with an oil pressure gauge , oil temperature sending unit, or fuel pressure gauge.