Early 1970 model year, cutouts in the underskin for the luggage rack only.
Early-mid 1970 model year, cutouts for the luggage rack & for go-wing style spoiler.
Mid 1970 model year, cutouts for the luggage rack, go-wing style spoiler & T/A style spoiler.
The last version has also been on every original 1971 Challenger I have checked so far.