Does it make the noise while parked in your driveway with the engine idling? Revving?
If it does make noise while parked, that would rule out differential (part of the transaxle), CV joints, and much of the transmission (part of the transaxle).
If it makes noise while parked, a conclusive test is to remove the drive belt (serpentine belt) and see if the noise is still there. If the noise is still there while parked, and with no drive belt installed, that rules out the alternator, drive belt tensioner, AC.
I don't know if your year ran the power steering pump off the drive belt, or with its own PS belt, but that's another easy test to do.
Another general method to isolate noises is to use a mechanic's stethoscope or a long screwdriver. If trying either of those, be very careful about moving pulleys / belts / etc. Can be very dangerous.
In general, tracking down noises like this can be surprisingly difficult, so be prepared to do some careful tests.