In the 1970 model year, California went from 999ZZZ to AAA001. When they did, the plate colors chaged from Yellow letters on a Black background to Yellow letters on a Blue background. Most people, when buying a used car back then, had the option of updating the plates to the current normal plate. (In california today, this is a blue letters on white background with "California" in red.) There are over 20 current plate styles in California. Anyway, when a car is rescued from "salvage," i.e. junkyard, it automatically gets new plates. The indication that it is a "black plate car" usually says that it was first registered in California, and was not brought there from another state unless it was less than 3 years old (in the case of a 1967 'Bird), and was not rescued from a junkyard.
