I believe Purdue had their own charter airline at the time, and they provided pilots for Playboy.
Ozark provided maintenance at their hanger in STL. My uncle was an Ozark Cpt. and would often take me through the hangar. On one occasion, the Playboy -9 was there. Very striking in appearance compared to the typical airliner Some resemblance to the Braniff "jelly bean" livery of the day however. At least the black ones.
This would have been around 1970-71.