Any Pontiac guys on here? Need insight.

The noise you refer to, just so we agree, is the noise that starts after the engine is running, after a pause, then I hear a "scraping" sound start.
Is that it?
The delay is curious, as if vacuum, wind, or centrifugal force moves something onto a moving object/disc.
I'm thinking some creature got into the converter cover, and built a nest up in the starter drive area, jamming the starter drive in, hence gear noise. Second, dragged **** in there and ????
Converter and crank pulley are only things moving if belts off .
The other thought about the delay is vacuum to the booster, check all hoses, it's like it builds vac, then sucks,
I don't have the best speakers .
Good hunting,