Originally Posted by Brett
it sound rough, and at about 50+ it's even more noticeable. sounds like it's getting worse as time goes by. it even feels jerkier at parking lot speeds than before. a bad launch could really contribute to this
Still have my number? I might be able to listen over the phone and tell you what I think.
If it's a whine or a marbly sound, it could be the transfer bearings. One thing to test is the center diff - go for a highway drive for 20 minutes or so and then try to do figure 8's at very low speed (near lock-to-lock turning) to see if it binds - the wheels will feel like they want to hop among other things.
If this is the case, buy a new center diff and transfer bearing set (~$620 or so). There's plenty of help in the MD to do this job at home. Don't bother with a trade-in, you'll lose money on the taxes alone vs. fixing it.