I know this is a really old thread but, being that we now officially know for sure what this crazy sound was coming from, I thought I should post an update... just in case you ever get it. As some of you know, we replaced Moby's ProRock 60 rear axle with a ProRock 80 when we upgraded our 3.8L motor with a 6.2 LS and, rather than selling the old 60, we decided to hand it down to Rubicat. Well, about a week ago, we had the axle installed and as soon as it was in, I got a call from Off Road Evolution asking if we were having any issues or noise coming from our transfer case. Confused, I asked Cindy if she was aware of anything and as soon as I did, she closed her eyes and told me to ask them if there was any chance the sound was coming from the rear axle... the one that used to be on Moby :doh:
Upon initial inspection, everything looked okay. Ring checked out but, there was a suspicious shiny wear mark on the teeth that warranted further inspection. And, after pulling out the carrier, this is what they found...
Needless to say, sound has a way of traveling. And, even if everything looks okay with your ring gear, it helps to pull things apart and give everything a harder look. Anyway, if you ever have a sound like this on your Jeep, you'll now know where else to look for it. Hope this helps you out.