99 rodeo engine squeeling from the rear

Our 99 isuzu rodeo engine is squeeling, but the noise is coming from the rear of the motor. The noise is what you might expect from a loose belt or bearing but they appear to be all up front. The pitch does change with the RPMs. What might be making that kind of noise from that location?

The only think I can think of is that your EGR is plugged and is whistling

or
your intake manifold gasket let loose and and is whistling

Bad intake manifold gasket is my guess as well. They can give off a squeal,screech,hum type noise when they develop a crack. Air gets sucked through the crack causing the gasket material to vibrate like a reed. You will notice it most at idle/low throttle (hi vac) conditions.
G/luck
Joel

Need More Info Cant Help If I Dont Know What I Am Trying To Help With (what Engine Is Planted In This Pig)