hey what's up ,i had that problem when i first got mine ,which i got used with 32k miles ,the noise for me after driving multiple times to duplicate noise turned out to be my p/s main engine mount studs from engine block loose ,causing a heavy clunk when moving off of coming to a stop ,but mostly heard when moving off ,just my 2 bits ,may help or not ,good luck.
hmmm. please elaborate on this for me a little.
i've been having a similiar issue and was ready to start a thread. i've had my car for over two years and have been dealing with this and theorizing on what i could be.
for me. it very much feels, sounds and seems to be a binding issue of some sort. it only happens when downshifting while coming to a stop. and only happens downshiftng into second gear most of the time. occasionally 3rd. but, and theres a but here, it doesnt do it so often if i rev match the gear. i rev match all the time. but when i dont its gauranteed to happen.
at first i realized that the stock motor mounts are very soft and the motor moves a lot. but upgraded motor mounts didnt fix it.
then i moved on to the rear diff. inspection after inspection i could not find a visible indicator that anything was wrong and everything felt solid. so i swapped in a TT rear diff brace anyway. nothing.
just recently i decided to try the hand brake (fwd mode) trick. figuring if it doesnt do it that at least narrows it down to the rear diff. or its supporting hard ware. and no clang, bang, nothing. i can dump the clutch while slowing down and it still dont do it. but soon as i let the hand brake back down(awd mode) it does it immediately.
i've printed out some info on the inner workings of the rear differential to study. i'm wondering if theres a problem with the shims or something. i'm not well versed in drivetrain parts so i figure that may be a good place to start.
please post up what comes of your dealer visit. what ever it is, its very annoying. so bad, sometimes i wish what ever it is it would just break already that way i could fix it.