[shammus]

I checked my previous thread on this which contained the closest tidbit of information that I've seen so far that could count towards a confirmation. This is from Bob Lemke -

Originally Posted by archive

posted by: bob lemke

Since i originally compiled and maintained the checklist for w590 in the standard catalog, i'd guess the roy spencer does exist. On checklists for "incomplete" sets like that, additions were (usually) only made upon visual confirmation of an example. After all these years, and without access to the old files that may or may not have survived my departure, i couldn't swear i ever saw an example, but my cataloging methodology at the time suggests i did.