ZG Driveline issues

[RayB]

Hi there,
Happy New Year.

I'm hoping for some advice please.
Attempting to get the old bus fit for a week or so touring Vic high country, she hasn't seen much use for a fair while now, its had a whine from somewhere in the drive line which has progressed to a thump/clunk when under load, gets a lot worse when turning.
Last time out left side CV started to "twang" when pushed hard, replaced both axles/CVs.
So far I have:
Checked for movement.
Changed both diff oils, no signs of metal, both appear OK to the untrained eye, couldn't see any pitting/scoring etc.
Changed TC oil, came out clean.
Dropped front drive shaft, no play in joints, outputs at diff and TC seem fine, turned diff by hand, smooth and easy, noticeable backlash, guessing that's normal.
I could not turn TC by hand with it and transmission in neutral, is this normal?
I suspect either the viscous coupling or the Rzeppa joint on the drive shaft maybe my problem. I removed the Rzeppa from the shaft, cleaned out grease, can't spot anything amiss.

Can someone point me in the right direction.

Cheers
Ray

[RayB]

I must have had a bigger New Years Eve than i remember, forgot to say with drive shaft removed it drives fine, no clunking or whine.
Thanks

[Siggers]

I think from memory the TC bind up, giving a locked style centre diff, this could be your issue, drop both tail shafts and give it a turn, see what comes of that, also could be the tail shaft itself.