1992 Lumina TH125C Transmission whine problem?

I have a 1992 Lumina with a TH125C transmission w/113000 miles. The transmission has a whine to it , mostly in low gear, or at least most notable. It is less prominent in 2nd and 3rd, but yuo can still hear it. It seems to shift just fine thru all gears, and does not slip at all.

When the car is hot, it seems to be even loader, and often.

Any thoughts on what this can be. ?

Welcome to AF, 4cyl?,