Okay so I've been dealing with this issue for about a month now and I've tried searching and reading every thread I could about various clunks in the drivetrain but none of them seem to be the same as what's going on with mine. First of all, I have an 06 GTO with a manual transmission with about 70,000 miles and its basically stock. This problem happens whenever I first start driving, it doesn't matter if its been sitting all night or for a couple minutes but it's only when I first take off and start driving and within a couple of seconds, theres a loud clunk that sounds like its coming from under the center console area and once it happens, it won't happen again unless I park it. I've crawled under it a couple times and tried to visually inspect everything and haven't found anything out of the ordinary, the transmission mount looks fine, the bolts for the rear control arms are tight, the u-joints appear to be fine, and I've check the center driveshaft bearing and it appears to be fine, its only when I push up hard on it that I can see the rubber around it is starting to crack a little. Does anyone know how much movement is normal in the center bearing? I can pretty much push and pull it in a circle around the loop, is it not supposed to move at all? I'm just at a loss because it'll only happen when I first start driving so its hard to tell what's going on, sorry for the long post and any help would be greatly appreciated, Thanks!