Not so good vibrations

[Polo1963]

Hi all

can anyone on here help with this please, I have problems with my polos front end regarding vibration. I have gone through all the usual and obvious reasons, tyres, wheels, ball joints, right through to replacing inner and out cvs on both sides.
I have had the problem diagnosed as being something to do with the diff, reason for this even with brand new and just replaced cvs after a week and less I have movement up and down on both drive shafts.

If you move them hard enough you get a mechanical clunk, now I know you should have a little play in the CV's, but it seems I have rather too much.

Is there anything that can be done from the outside of the cat to sort this, or am I looking at the gearbox out and repair / replace.
The vibration is constant and is slowly getting worse, personally with all the work on the front end I can find no other reason for the problem.

Could someone with better mechanical knowledge and experience of this problem, or who understands this better than I do please confirm what i need to look out for or confirm its a gearbox out job.

Thank you