I agree with Andrewl.
I have spent a lot of time in the US and am fairly well read up about cars and I could not even begin to take you through the myriad of spec's and model changes for the '67-'69 Dodge Charger ( a well known car, of which lots were made and share the same body, the same 'B' body of the Coronet) let alone all of the millions (literally) permutations of Mustangs.
The US car industry is much more short term and fashion driven than the rest of the world.
The boot is often on the other foot, I have seen many a 12 valve BMW 528i sold as a M5 in the US, and any Turbo Volvo wagon passed off as a T-5 R.
Most US car clubs are 'Real Friendly' and will help you through the pitfalls and tell tale signs of any model car you choose (did you know that there is a Plymouth Super Bee club. Not bad for a car that was in production for 9 months! :shock: )