Is it a mechanical whine, do you feel a vibration anywhere?

Not sure on mechanical, it almost sounded like a supercharger, so much so that I pulled off my air filter (it has a K&N intake from prev owner) for a test run to make sure I wasn't just hearing the air being sucked through the air filter. No vibrations.

Do you have a check engine light on?

No.

Could it be a vacuum leak that you're hearing?

I'm skeptical but it's possible. It would have to be very high pressure, it's quite loud. My cruise control is out too even though the electronics work so I do suspect I have either a vacuum leak in those lines around the intake manifold or the servo under the battery is out. But I couldn't imagine that tiny vacuum line making this noise.

Is your radio on when you hear the whine?

No, it's not a bad ground sending engine RPM noise through the speakers. I do have a tiny touch of that but it's not the problem.

When was the last time your transmission was flushed and differential fluid changed?

Not sure, may be in the previous owner's records, but I've got the diff fluid in my garage, been meaning to change it. I've been avoiding servicing the transmission because I suspect it's near the end of it's life and I don't want it to fail right after service. In my experience servicing a tranny that is close to death usually is the straw that breaks it.

So you hear it at WOT at above 4500 RPM while under load, do you need to drive your WJ that hard?

No, I basically never drive it that hard, maybe once every six months. I'm just trying to resolve any solvable issues. There were a lot of little problems here and there that have started to accumulate and were detracting from my enjoyment of it and I wanted to clear everything up. I've taken care of most everything now aside from the cruise control, heater core, and this whine.