I vaguely remember having a split in my transmission mount that allowed the tranny to move about under load. I think it caused noise on my ball and trunion (1964 manual trans).
In another instance of a similar noise I had after a night at the drag strip, when I reinstalled the exhaust pipes to the header collectors I didn’t rotate the assembly on one side far enough away from the driveshaft. It made a noise of a higher pitch than what is on the audio.
If you have headers, check the collector gaskets.