I have a 1995 Wrangler Rio Grande 2.5L, 2.5inch lift, 30inch tires. I have
166,000 miles on it. I keep all fluids changed and she runs and drives great. recently I have noticed that after driving for about 20 min I will hear a ringing/gear whine above 40mph and will go away at about 65mph. When I let off the gas the noise goes away then comes back when I get on the gas. At around 45MPH the noise will sound really loud and have a high pitch resonance. When I go into 4wheel drive there will be a slight gear meshing noise but the ringing/high pitch noise is almost not there. The Transmission runs great in all gears. This noise is not engine RPM related and when in nuetral reving engine does not make noise. When I changed my u-joints thinking that they were causing it I was able to spin the rear yoke. There is no in and out or side to side play in it and there is no noise when spining wheels on jack stands. There is about 1/8 inch back and forth play between the teeth of the ring and pinion gear. Last gear oil change 4 months ago and all oils in front/rear diffs, transfer case, Manual Transmission where clean and metal free. I have another transfer case that I am going to put in when I pull the old one to replace transmission rear seal that is weeping. It almost sounds like it is coming from under the shift knob area and under the seats.
Just need some direction before I start randomly throwing money at this thing
Thanks Everyone and Happy Jeeping