I sort of disagree. My original 273 Dart when I bought it fit that. After scoring better T bars (used), new, better shocks and radials, replacing all the worn parts AND ADDING a factory anti sway bar, and then rebuilding the rear leafs, that was a COMPLETELY different car
NONE of what I did can be considered aftermarket except maybe the shocks and tires, which were still not "specialty" race/ performance items