Exactly what makes a MOPAR a "Matching Numbers" car?

Both of these cars of mine are numbers matching cars IMHO.
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Now the Dart has headers and non factory exhaust, alternator is a replacement and intake and carb aren't correct but it's still a #'s car.

The Bee on the other hand is more #'s matching as even the alternator and exhaust manifolds are what came on it new, with a full factory correct exhaust system to boot. The wheels are CTC from 1978, but I do have the original full wheel covers it came with from the factory... just not the steel wheels they go on.

Then you get to the down right craziness of finding tie rod ends and ball joints that are factory NOS, but to me that "value wise" changes nothing as even those over the counter NOS parts from the service shelves aren't assembly line components.