'orrid vibration

[totta Crolla]

coming from drive line. Between 5000 and 6000rpm approx. and more violent in 5th gear for some reason.
I have put the car on stands, removed the wheels calipers and discs and then run the car through the gears.
Could it be the flywheel ? I have recently fitted a lightened one.
Gearbox maybe ?
The vibration is bad enough to ensure that on the track I don't go beyond 75mph as the car feels just awful.
The rear wheel bearings are fine and a new propshaft centre bearing was fitted 3000 miles ago together with a new modified (to suit Ford gearbox) and balanced propshaft.
Thanks for any help.
TC

[oldeskewltoy]

clutch out of balance???

input shaft bearings?

[totta Crolla]

I think I have an answer and you won't believe it
Whilst inspecting the propshaft centre bearing I noticed some fairly heavy denting on the exhaust, it is hitting the propshaft middle joint flange I will arrange for more clearance with the exhaust and see what happens, could be a cheap easy fix..... fingers crossed
Or it's gearbox related and probably the tailshaft housing bush......
Anyone know how much lateral movement there can be in the propshaft centre bearing bush ?
Thanks,
TC