If you are talking a 65' Riviera GS than the 2x4 was an option, but I don't think it was an option on the GS (skylark). The aircleaner housing should read Wildcat 465 for a 425cube motor, which the 2x4 option was available for, not Wildcat 445, which was for the 401. I stand to be corrected, but I don't think your getting the whole story here, as things seem to be a little mismatched.
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