I found this particular gem because it's just one minute past a much more important historical artifact: confirmation that the IRIG-B time signal encoded on the MOCR tapes is lock-step with the clocks used by the human controllers and support crew. Just a minute before this barter there is an exchange between Houston Recover and Pacific Recovery where Houston clearly counts down the GMT and GET clocks so that Pacific Recovery can adjust their ship clocks to match.
In the attached annotated spectrogram, the speaker speaks the phrase "eight, nine, MARK, 50 seconds". Below each utterance are the time code markers output by the IRIG-B decoder software that we wrote for Apollo In Real Time. The "MARK" phrase lines up perfectly with the GET timestamp "33:53:50" / GMT timestamp "1970-04-14T05:06:50".
https://apolloinrealtime.org/13/?t=033:53:36&ch=33