....don't necessarily take your mechanics word that you need a new driveshaft!!! Unless the 'supporter' he is talking about is the U-joint. It's usually the U-joints that go bad on driveshafts, not the shaft itself. Did your mechanic check the 'transmission mount'. If that is shot, which is pretty common with high mile cars, that could be the source of your vibrations. You might want to look a bit deeper to find the problem. Also, besides what Carlos said, Carbon Fiber driveshafts are available as well for the Z, however, they are between 900 and a thousand dollars........