This looks like a bit of a thread hijack, although in the same subject so I'll chime in.  
 
   
I read the following on WA DOL regarding the qualifications for using restored plates: 
"Washington-issued license plate that was designed for use in the year of the vehicle’s manufacture"
Link: 
WA State Licensing: Collector vehicle plates
Anyone know how flexible the DOL is about this clause?  I'm hearing that this aspect can create a hassel, although we all know that it is often who your working with at the licensing bureau that dictates.  
I like the antique look of the "WASH. 63" plates and this was the only license plate made with an abbreviated reference to Washington, because the great people of the state felt it was not a dignified abbreviation reference to our wonderful Washington.   

  But, since my Cobra is titled as 1966, based on my limited understanding and research, this DOL clause means I can't use the "WASH. 63" plates which were issued in the years of 1963 and 1964.  Does anyone have any wisdom or personal experiences to share on this aspect of matching plates with the car's year of registration? 
Fortunately if DOL is a stickler on this matching, the 1966 plates I need started being issued in early-1965 (as they ran out of WASH. 63) until sometime in late 1967, so there should be more of them available 
 
I found a site run by Ian Slade that does a good job documenting Washington State licenses by years, counties and the background histories of the different plates.  If anyone is interested here is a link to one of his very well done pages:
WASHINGTON County-Coded Passenger Plates, 1958-1981
More on restored plates and what DOL wants:
WA State Licensing: Restored plates
Good luck finding your "special" plate.  
Cheers 
BC Kevin