Just amazing how many of those WPE numbers were given out!!
And it only lasted about 10 years or so, with the successor WDX hanging in there for another 2-3 years. It didn't survive the mid '70s IIRC.
Mine was WPE9JZT, received the same week as I received my Novice license (WN9EAZ) in May 1970. I never bothered to "upgrade" it to WDX since wasn't official anyway.