More rear axel noises

Hi
I’ve searched the forum and found possibly similar problems but nothing that reads exactly as I’m experiencing, I’d really appreciate thoughts on what the problem could be.

I recently had a new clutch fitted with no issues until about 2k miles after when the “main” bearing for the prop shaft gave up resulting in a hole in the transfer box (IRD?) case. Whether this was a result of the work done by the clutch replacement I don’t know. The same garage then replaced the transfer box (and the VCU) and again OK for about 1k miles.

The latest issue, and what I’m looking for some advice on occurred as I was off the throttle coasting downhill (so under engine braking) a noise started which sounded like a plastic bag caught in the prop shaft, a sort of intermittent whooshing which increased with speed. There was/is nothing caught anywhere in the drive train. When I continued to drive the sound eventually became a constant whoosh (no rumbling or vibration) until it suddenly stopped after a few miles.

The noise does come back occasionally, usually while going round a roundabout under load, it is definitely coming from the rear diff area (I’ve sat in the boot and listened!)and I can get the noise to stop instantly just by reversing a few feet.

I think I can detect a rumble when coming off the gas and letting the engine/transmission take the load but I may be mistaking road/engine/transmission noise for this.

All work was done by a standard (non LR garage) I’m thinking of taking it to a stealer to check the whole drive train through, or a I may just sell it off (which I don’t want to do as I like the vehicle and I had it LPG converted).

Any ideas where I should be looking or should I just pay the high stealer prices??
Thanks

id check your viscous coupling isnt sezed ,by jacking up one rear wheel and turning wheel with bar on wheel nut ,its more likely cause of ird unit breaking and bearing failure ,though you would have supposed garage would have checked it ,if cv/c is seized you can remove whole prop assembly and drive it in 2wd ,

Thanks for the reply.
The VCU was replaced with the IRD and cv joints checked, I may go for 4x2 just to test but will want 4x4 at theend of all this. Am thinking go for a low level service to diff but this is just a guess.

diff would have had extra strain as well as ird ,changing the bearings in the diff isnt to expensive or hard if you have tools and knowledge if caught before too much damage ,presume youve checked obvious stuff like a rubbing brake shoe etc

The garage that checked it did look at the brakes, they acknowledged a noise that they thought was coming from a wheel but certainly wasn't wheel bearing.
I'll go for the diff bearing I think
Thanks