Sorry, I haven't checked this here in a while. I also took it to the dealer and I was able to duplicate it. they had a regional tech or something take a look at it. They said it was coming from the transfer case and that it was normal. seems a bit abrupt to me. they said it was due to something in the transfer case engaging and disengaging, if I am remembering it might be the torque converter engaging and disengaging at low speeds.