Took my 87 Cherokee on a small dirt-road adventure. When I got back to pavement, I seemed to have developed a strange whine on my engine. I notice it most when in neutral, or when first pulling away (probably can't hear it after that due to custom exhaust and road noise). It is very loud when cold, but it is there no matter the temp. It is connected with the engine...it is there weather moving or stopped, in gear or out. It increases in pitch as you idle faster. The only other symptom I've had is that my voltage has started dropping and coming back up while driving down the street, with no apparent patter to it. This may be unrelated or connected, I have no idea. Everything else seems to run fine, including the coolant system, belt, 4-wheel drive, power steering, etc.
Hunting season is next week, and I'm hoping not to get stuck somewhere. Any ideas?
Thanks!

Sounds like one of your pully bearings for the fan belt. ie: alt, tension, idler, power steering, water pump etc.
If you went through water or mud I would bet thats the problem.
With your engine running, try squirting a little WD40 directly under the bearing area of your pullies, one at a time to isolate the offending bearing.

Ya it sounds like it could be the alternator bearing or one of the other ones. You can try using the poor mans stethoscope to find where the noise is coming from. Take a 3-4 foot garden / heater hose, put one end to your ear and poke around your running engine with the other end. Make sure you check all around your alternator. Using this method should help you pinpoint where the noise is coming from.

I would check alt 1st, especially since you mention voltage fluctuations.

Jeff