Feels knobbly going into 5th?
 

Ok wierd description of fault. But my 99 turbo with 108k on her has recently started to feel a bit "knobbly" going into 5th. More so at high revs. Lower revs or if i pause when changing its fine. I have no more issues with it, Bar say a bit crap going in reverse a times i have to lift clutch a few times. But it seems it's always been like that.

Is this syncro?, im pretty clueless regarding gearbox.

could be syncro or the nut backing off at the back of 5th.