The 13 character identifier is what defines the car as unique.
Example V.I.N. :
S S 22 L 9 R 123456
From this V.I.N., we can tell a few things about the car, which in the case of the 1979 Chrysler 300, applies to just about each one made except for maybe the 7th - 13th characters.
S - Indicates the car-line.
S - Indicates the price class.
2 - Next 2 characters, "22" indicate the body type
2 - "
L - Indicates the engine ( L = 360-4 BBL, but so does one other letter)
9 - Indicates the model year, 1979
R - Indicates the assembly plant ( R = Windsor )
However, if the ifnormation I received about the 1979 Chrysler 300 is correct, then the Sequence Number doesn't necessarily mean that the example above is the 123,456th 300 made, since we have to believe that there were only about 5000 made.
If anyone knows differently about this, please contact me immediately.