OLD CALIFORNIA LICENCE PLATES

California changed plate size, shape, and color in 1956, to the universal size and shape now in use, with black letters on yellow background. It will have 56 stamped into it. In 1963 they flipped the colors to yellow letters on a black background. They have 63 stamped into them. Somewhere around 71, i'm not sure exactly, they switched to yellow on blue and swapped from three letters then numbers, to numbers then letters.
The black on yellow are valuable to the finned crowd, and shoebox chevys, the "black plates" are wanted by the late sixties musclecar crowd.