case in point, when I ordered parts for my disc brake swap, the inner wheel seal I ordered was correct for the year of car (even cross references the same as the F body part), BUT the replacement discs that were "correct" and listed for a 1976 duster were actually machined to use a larger diameter inner wheel bearing seal that I think happened in the early 80's-- the part number needed cross referenced to a mid 80's 5th avenue....