draging noise while not moving

I have a 1996 tahoe 106000 miles. The other day in normal driving as I turned the corner it sounded like I was draging cans. When I straighten the wheel it still sounded like I was draging cans. I stoped the truck and shut it down. I looked under the truck and there was nothing draging.
I then started the engine up and the noise came back. I put it into Neutral and the draging noise was still there. I turned the engine off and restarted it and the noise was gone.
When I got home I looked under the truck and I saw nothing lose or in the way.
I driven the truck since then and the draging noise has not came back.

What could this noise be?
Clutch Fan?
Flexplate?
In the exhust?

Thanks

Where did the noise appear to be coming from? When your cat dies, it sounds like a can full of marbles. Crawl under your truck and knock on your cat. Does it rattle inside? It shouldn't.

Thank you for you suggestion

Checked the cat. No rattle. Looked around the fan and it has not been hitting anything.

The starter went out on it in between messages. The noise happened for the fix it shops people. Of course this happened after the starter replacement.

They said the flywheel is bent.
Could this be?
Thanks