In 1964 Mass switched from issuing plates in odd years to even years. This was due to poor paint that was used on the 1963 paints that cracked and peeled. (Some stories attribute this to prisoners urinating into the paint, while others chalk it up to corrupt bidding on paint. Like the 28/29 fish story, this one has also seemed to take on a life of its own!) Consequently, nice looking 1963 plates are hard to find. Again in 1965 no dated plate was issued, but those issued to new registrants in 1965 had a W prefix.

http://www.w-a.com/maplate.htm

http://www.dmv.org/ma-massachusetts/license-plates.php#Antique-Plates

http://www.massrmv.com/rmv/forms/20132.pdf