Re: idle noise
The noise you describe is a normal characteristic of the NV3550 trans used in the TJ for 2000. This trans is basically the same as the NV3500 used in Dodge and Chevy trucks since'92 or so. The NV3500 I used in my CJ8 makes the same noises you describe. Because of the noise, the trans hasn't been available in the 2000 XJ yet. Chrysler is also giving auto transmissions away as a no cost option in TJs the last I heard. The dealer won't be able to change the noise level by swapping parts unless the factory comes up with a fix. Don't attempt to use heavier oil to quiet the noise, as durability and shift quality will suffer. Hope this helps!
P.S. This trans is a strong unit that will give good service despite the noise level.