Notorious on the Z-Cars is the mount insulator on the nose of the differential. They are of a poor design and break all of the time. I would put money on it that yours is broken. To check, you will need to jack up the car and use a pry bar to lift the nose of the diff. You will be able to tell if the mount insulator is broken right away. I recomend using a solid mount, but they increase the noise from the diff. Or you can get a stock one from the dealer for about $45. Good luck.
> My first Z and every time that I accelerate
> quickly the rear end sounds like theres a
> sledge-hammer pounding under the back of the
> car What Causes this?