Vibration through shifter at 3000-4000, any ideas??

[maddogg20]

I have a 98 GT with a 5 speed. Anyway when i rev it or drive it, from about 3000-4000 rpms, theres a really weird sounding vibration, that I can feel though the stick, but I'm not sure what it is. Someone said it may be the U joints, but I was thinking that if it were, that it wouldn't do the vibration in neutral. Any ideas???