mine clunks from the steering column going slow over patched pavement...Not sure if my rattle is the same, but mine sounds like it originates behind the instrument cluster also. Seems to only be really loud in warm weather with speeds around 40 mph, maybe up to 60mph on occasion. (I had a video posted on here, but I haven't yet figured out how to find posts I've made.)
Dealer was supposed to investigate when I took my car in for the power steering recall. When I picked my car up, the service guy said everything looked fine. Rattled on the way home. Tore apart the dash as best I could and couldn't find the culprit. Even drove around without the instrument cluster removed. Still rattled.
You have my empathies. The noise in my car is driving me nuts. My only solace is maybe it will stop in the cooler weather.