How do I identify a 'cuda?

Easy as pie. 67's do not have side marker lights, 68's have round ones and 69's have rectangular ones. Also, 69's do not have inserts on the hood, 68 inserts call out the engine displacement if it's an "S", 67 inserts are all the same.

An "S" car is just emblems, heavy duty suspension (available on any model) and the performance engine. 67 would either be the 273 4bbl or 383, 68 would be either the 340 or 383 and 69 would be either the 340, 383 and I believe you could get the "S" with the 440 but not sure.