My 1995 Z28 automatic has been making this noise for several thousand miles now. Whether in gear or neutral, engine on or off, as it rolls forward, it makes a clicking sound that increases with speed. At 10-30mph it sounds like a gear drive timing set through my transmission tunnel. By 50mph, it is so fast that it dissapears into the exhaust note. Slowing to a stop, it becomes more annoying as speed decreases. Is it something within my tailshaft, part of my driveshaft, or possibly within the rear end? With engine off on jackstands, I cannot spin my wheels fast enough to get the sound. Has anybody anywhere ever had and fixed this kind of sound?? thanks, edman

 

On the chance that this noise is being produced by the tranmission, I'm going to "copy" this post to the "Drivetrain" forum. We have a reliable trans rebuilder that drops in once or twice a week and offers help.

 

You could always put the rear end on stands and run it like racers used to do to heat up the fluids. Just don't pull a Ferris Bueller.

IMO, it's either a bad U joint or you've busted something in the rear end.