Hideos Transmission Vibration

[yellowgibbon123]

I own an Audi 80 1.9 tdi, its done a stack of miles 211 thousand to be precise, doesn't use a spot of oil and runs great but it has developed an awful vibration to the point of being undriveable. Driven fast with the revs kept high its fine but drive normally changing through the gears as normal it develops an incredible vibration that shakes through the gear stick and through the whole car to the point that something sooner or later is going to break.
Does anyone have any ideas whats causing this.

Here is a list what i have done to try and fix the problem

Inector pump removed and checked out by 3 different people including an Audi main dealer
New Injectors
New crankshaft pulley ( vibration damper )
New crankshaft thrust washers including main bearings and big end bearings while i was in the sump
New lower supsension arms
Rear axle bushes

At the moment i have the gearbox removed but I can't see anything wrong with the flywheel clutch or gearbox, the driveshafts have very slight wear but nothing major.

I have now given up, the main dealer had the car for 2 weeks and couldn't find the problem.