What I've found with CA DMV plates from the 1960's is that it often depends on how one originally acquired the plates and/or where the car was purchased. If you bought the car in a large metro area, then it usually followed that 67 plates would typically begin with T, U, V; 68 - V, W, X; 69 - X, Y, Z. More or less.
But if you picked up plates at an office out in podunk (e.g. San Andreas, Jackson or Placerville, CA for example) you might be issued a plate with a much earlier letter in the alphabet since those offices may not have exhausted their distribution of plates issued to them earlier.
I grew up in Calaveras County, California (podunk) with the closest DMV offices being Jackson and San Andreas. I distinctly recall late '60s cars purchased from dealers in those towns with plates beginning as low as "A". Yes... I was geeky back then and paid attention to this stuff. On one of my treks between home and college in San Luis Obispo back in 1977 I saw a '67 GTA fastback looking identical to mine except a black interior in Valley Springs, CA with a plate beginning "AEC" while mine was/is "VUT". I later learned that the car had been purchased from Stewart's Ford in San Andreas in 1967.... about 12 miles from Valley Springs.
So based on my observations since at least 1974, it is plausible that very early '60s plates can be original to later '60s cars.
