This is a Packard Bell Phonocord. It has a metal core and is about 8-inches in diameter. This is another Grinnell's acetate. They were a music store based in Michigan. This disc is unlabeled but is clearly a radio recording.
Peggy Mambo
It begins with a woman singing with a small mambo group. Despite the record hiss you can hear the clave clicks. I'm no mambo expert but at about the 2 minute mark the DJ comes in and tells us that the singer is Peggy something. That pretty much has to be Peggy Lee or Peggy King and both of them cut mambo songs in the 1950s.
He doesn't give the call signs but he does tell us that the time and temperature. He they reads an ad for a local card company but then the audio cuts out just as he's abotu to give the street address. Damn. The ad is for the RP Lewis company... and there is one of those in Ann Arbor which lines up with the make of acetate. That's my only clue.