My friend has a 2000 Mustang GT. There is a loud squealing under the hood and we think it might be the belt or some kind of berings? What exactly is it?

 

Typically a squeal means you either have a belt problem or the power steering pump is low on fluid.

 

Remove the belt and start it, if it stops squeeling it is something belt driven, not the engine.
Turn all the pulleys/idlers by hand and feel for any roughness or side to side movement.
Be careful, if a pulley has a bad bearing it will be very hot.

 

Like stated above it could be a worn belt, alternator bearing, waterpump bearing, or low on power steering fluid.

 

is this squeal when the engine is under load, or when it is at idle?

 

i have a similar sound in my 99GT, however something makes me think taht it is not belt related

the sound is audible at idle more than anything else, especially outside the car.

but its also evident between every shift, RIGHT as the clutch fully releases.. any suggestions?