(updated June, 2016) This article was published in The Vair-iety, the newsletter for Corvairs Northwest, in 1997.
During my quest to learn about the various special licensing programs that Washington State offers for my 1966 Corvair convertible, I uncovered a mistake in the Department of Licensing's chart of license plates. Fortunately, after several years of effort, the error was corrected in approximately 2008.
I have the original Washington plates for my 1966 Corvair Corsa convertible. The plates weren't on the car when I bought it. The previous owner fell victim to a short‑lived program in 1985 which required all plates with non-reflectorized paint to be updated to new, reflectorized plates. Fortunately, the previous owner kept the original plates in the hope that they could be used again when the car turned thirty years of age. They had been restored to a like-new appearance. 
The tabs for my convertible were due in January, 1996 so I went over to my local license bureau after the holidays and inquired about collector vehicle programs. The Restored Plates option sounded like just what I wanted. (Also see WAC 308-96A-074 for the full legal description.) Imagine my surprise when the bureau employees cheerfully informed me that I had the wrong year plates (1967 instead of 1966) and therefore was ineligible!
The Hunt is On
Not being one to give up easily, I started researching the situation. I obtained copies of the program requirements and the license plate charts. It seemed a little strange to me that all cars licensed for 1963-66 would have plates which read "WASH. 63". My plates exactly matched the description and picture for the 1967 plates.
After digging through quite a bit of documentation that came with car and talking several times with Kathy Rambur of the Department of Licensing in Olympia, we verified that:
- The car was manufactured in the fourth week of May, 1966
- The car was delivered on June 16, 1966 to a Washington buyer by the Bill Hazelett Chevrolet dealership in Kent, WA
- There was no "previous plate" listed either in Department of Licensing's or my records 
- The number of the plate I wished to use matched the number on all of the records that the Department of Licensing and I possessed 
- The plate number was very low (within the first 16,000 plates) for the "WASHINGTON" series for King County
My records went back to 1976. The Department's went back to 1972. Since neither of us had a copy of the 1966 registration, we couldn't be certain that the plate I wished to use was the original. However, it is very unlikely that the "Previous Plate No." field would have been blank on the 1972 registration if there had been, in fact, a prior plate.
Will the Real 1966 Plate Please Stand Up?
All of the evidence pointed to a mistake in the Department of Licensing's charts, namely that they actually started using the "WASHINGTON" plates once they ran out of the "WASH. 63" plates.  (A fantastic collection of plates assembed by Ian Slade confims that King, Pierce, and Spokane counties started using the "WASHINGTON" design sometime in 1965, while some lower-population counties never did use them.)
I then contacted Peter Madsen, a long-time license plate collector who lives in Olalla, WA. He was kind enough to write a detailed letter to Kathy and me that explains the situation. Fortunately, Kathy at the Department of Licensing agreed with my assessment and Peter's evidence. I was allowed to use the original plates.
Note: Although the car was purchased in June, 1966, the tabs were due in January because the previous owner took the car out of service for about a year and half while he was restoring it. He chose to return it to service in January.
Good News Everyone
Although I was successful, Kathy told me that her management did not have enough evidence to officially declare an error in the license plate chart, even with Peter Madsen's letter, After a few years, however, their point of view changed and it became a matter of waiting for budget to produce and distribute corrected materials. Beginning in about 2008, the Department of Licensing was finally able to create and distribute the updated materials -- in the form of a brand-new document titled A History of Washington State License Plates. This is a PDF that is on the Department's internal network (intranet). Today, when you ask to register a vehicle with year-of-manufacture plates, the clerks at your local license agency should be referring to this PDF. My local agency was happy to show it to me in 2016 and I verified that the info for 1963-67 is correct. 
 The restoration was done by Anthony V. Polio, 746 N. Greenbrier Dr., Orange, CT, 06477. Subseuently, I have had very good results from Bjorn Larsen at the Old License Farm, which is conveniently located less than an hour from where I live.
 There is a field on the registration called "Previous Plate No." that will list any prior plates. It was blank on all of the records for my car until 1985, when the non-reflectorized plate was removed.
 You don't have to use the original plate, just one from the correct year, but since I was trying to prove an error in their records, having the original plate was important.
 Kathy also discovered a law passed in 1965 which required the state name to be spelled out on any new license plates. This law went into effect sometime in 1966 and hastened the change-over. Information I
 You'll know if the clerk is referring to the old, incorrect documents if they mention the numbers 9302 and 9303 -- those are the sections with the incorrect info in the outdated document, which is in printed form only. Thanks to Mike Sigler for informing me of the new PDF.