Now that I know a bit more about these recordings (solely from transferring and listening to them), I was able to dig up a bit more information on them from this site:
http://watchtowerdocuments.org/history-of-wbbr/
Radio programs occupied much of Rutherford’s time and he was unable to travel or organize conventions in various parts of the earth. So in 1931, the WTS decided to present transcribed programs. Two hundred and fifty stations were organized to present fifteen-minute transcriptions made by Rutherford at his convenience, and played by the radio stations at times they chose.
In 1932 this radio service (called the Wax Chain) was expanded to 340 stations. By 1933, the peak year, 408 stations were being used to carry the program to six continents, and 23,783 separate Bible talks were broadcast, most of them being these fifteen-minute electrical transcriptions.
In other words, there are theoretically around 408 copies of these records made. Most of them were likely tossed by the radio stations by the time they were finished with them. It's entirely possible that I have the only existing copies of these three speeches.
