Vibration from shifter @ high-rpm's in 3rd+ gears only !!

[jetuomi]

I've got a vibration/sound problem, only starts to happen really excessively in 3rd gear..

1st gear is fine upto 5500 rpm
2nd gear starts to make this metallic sound along with a bit of shifter vibration above 4500 rpm
3rd gear starts to make more of the sound and vibrations above 4000 rpm +
4th starts around 3500 rpm..
5th starts to make the same around 3250 rpm.

but, low rpm's, coasting, or revving down doesn't cause the sound/vibration. This is really really loud when I'm racing someone and shifting @ 4800 in 3rd, 4th, etc..

So, is it the driveshaft? Clutch? Clutch forks? Nothing has been done recently to the drivetrain (mod-wise) so I'm stuck for answers..

Thanks !!

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94 GT (triple black)
K&N, FMS 9mm, FMS 95 17" Cobra R's, 3.27, 12* timing, MSD Coil, 180* thermostat, MAC Shifter/Gauges/Pedals, Euro Clear Projectors & Corners
My CAR!
Email me: jetuomi@yahoo.com