Cory, yes, the year of manufacture plate is pretty easy to do and only a one time charge so the cost of the plate quickly pays for itself without the annual registration. I have a pair of 1963 plates on the Falcon.

Roger, the "A" signifies it was issued in King County. Apparently and strangely this was a one year issued plate for 1957. Although it says 54 under the 57 tab, the actual 1954-1956 plates were longer. In 1957 Washington decided to adopt the National plate size. They must have reused parts of the earlier die (including the part with the 54) until they could revamp the entire design in 1958.

There is a whole subculture of plate collectors that are over the top.

Here is an awesome website about Washington Plate History worth a few minutes of browsing.

http://staff.washington.edu/bbirt/