GQ Vibes

G'day all, I know this question in similar form has been asked alot but I have a vibe and sounds in my Patrol that are very annoying.
It started when I got my clutch replaced and we headed on a long trip. After 1000klms there was a sound and vibed coming from the drive train. Cause we were already on the trip we couldn't get it checked until Alice where we were told it was ok. When we got home it was worse so I took it to the mechanic who did the clutch, he couldn't work it out and was not being very helpful at all. He did put a new clutch(so he said) in it which fixed it again for anothert little while. From there it is worse. It is a grinding noise at about 900-1200 revs and then at 1500 revs it sets up a harmonic vibe through the car. When slowing down at lights in any gear at 1200 revs it vibrates and grinds you have to clutch in. This is way above idle and there should be no load on the motor. Now at above 80 only in 5th gear there is a vibration in the drive train that feels like a tailshaft vibe but at the exact same speed in 4th it is not there and then in 5th it is. Some other people have said input shaft bearing, others spigot bearing. I don't know but it is annoying and if I can't fix it which I do want to because it is a good rig then I will have to get rid of the car.
Thanks for any replies
Draff