I have an 04 3500 cummins 6spd ram and it does the same thing in 4x4, but only when your turning sharp, like when I am parking my trailer, I dove it to the airport and back to Riverton Tuesday night during the blizzard in 4 hi, 40+ miles @ 50mph with no problems at all, but when i got home and turned it sharp to pull in the drive way it made that funny pop noise. So I assumed its in the front end, typical Dodge. I also was told that the Dodge T case should be over filled at all times, my T case rear seal leaks and there is fluid all under the bottom of the cab, but the last time it was serviced at the dealer they said it was still full.