1970 was the most desirable one to have. Most H.P. Scooped hood, Biggest tire option, most rare.
1969 was the fastest in the 1/4 mile, per S/S Hurst specials.
1968 was the fastest top end thanks to Craig Breedlove's record breaking runs.

http://bangshift.com/general-news/vi...run-in-an-amx/ (Note, no rear wing/spoiler or front air dam.)

Later Breedlove took the AMX for a Land speed Record of 189 mph officially, and over 200 mph unofficially.

Would have been so cool if Chrysler had done something similar with the Crossfire when it first came out.