Presumably you're aware that vehicles built in 1998 onwards require two keys to program a third. Don't know if key chips are compatible with the earlier system, but doubt it.
My suggestion; park the Aviator for a week, drive the Contour, save enough on gas to pay for new key.


98 Mystique LS v6 atx 163,000km 97 Contour LX v6 atx 163,000km