brake battery parking brake lights, and a squeal

1988 240 DL. Brake, parking brake, battery lights on. I know this is often an alternator issue. But there is also a horrid squeal. Could it just be a belt?

It could be the alternator bearings are seizing or with bad bushings it is far out of alignment. Check for a charge light when the key is on. No charge light you need to check that circuit and fix the light. Then check for the alternator charging when the light circuit is working.