If I have my info right, here is a cross-reference:
BRISK # GOR17LGS – TR55IX – AL 606
BRISK # GOR15LGS – TR6IX – AL 605
BRISK # GOR14LGS – TR7IX – AL 104
Please research further as I know the TR55IX is an OEM plug and comes pregapped at .059, the TR6IX is one step colder and is pregapped at .039.