Although there are several non-U.S. mono releases of Francis A. & Edward K.
, it may have been issued in mono in the U.S. only as a white label promo LP (F-1024).
Added: But, I did find this February 3, 1968 Billboard
review, which lists the mono catalog prefix.
After that album, Cycles
, My Way
, A Man Alone
and Sinatra & Company
were also issued with mono catalog designations outside of the U.S. These are probably fold-downs of the stereo mix.