Squeeling Noise from engine area

'99 Ford Explorer w/97K. I keep hearing a squeeling noise somewhere in the engine. Never had any belts changed. What could it be?

The belts.

Ed B.

The old, dry belts are slipping. It’s time for new belts. It may be just one belt or it may be more than one, but it, or they, need to be replaced.

“Never had any belts changed. What could it be?”

You have asked and answered your own question.
Just reverse the order of your sentences in order to see your correct answer.