how to decode the sequence number

Also, you can tell from a car that has a high number like your V.I.N. is, you can be assured that it was built later on in the production year. (at that plant).
Remember, all cars built at that plant are included in the sequence that they were coming down the line (in general) and a Fury, Road Runner, Valiant, or whatever could possibly be sequential numbered cars.
However, they usually did build them in batches of similar cars though for the simple fact it was easier for the line workers to assemble them more quickly.