The interlocking letters used for the title on (S)X1011 and NXS1011 are hand-lettered, and don’t use a typeface – note that none of the repeating letters is identical. In both versions, Filmotype Falcon is used for the group’s name. The Diplomat logo uses Filmotype Zephyr. The song titles are set in all caps from what appears to be News Gothic (white on red) and Futura Condensed (green on white).
In 1971, Diplomat released a different album under the same title (SX 1708), with a similar lettering style for the title. This time, the letters are not custom drawn, but come from a typeface: It’s Filmotype Newton, see the end of this post.