Came across this while searching through a hand-rolled quarter roll marked '1965-66': I'm not an error collector, so I was just looking to see if someone could tell me something about it.
Very nice no date CUD! Here's a link to some others: http://cuds-on-coins.com/washington-quarter-cuds-no-date-2/
Take a look at the link Jay posted. If they don't have an example of this one already, then you should them the photos. I'm sure they'd like to list it.
It can't be a 1965 or 66 though because they didn't start using the P mintmark on the quarters until 1980. There is a 1982 P I believe though that comes with this cud.