110 expensive sounding noises and wonky rear axle- Help!

Hi guys, i'm still pretty new to this game, and could do with some advice.
Recently my 200tdi 110 started making a grumbling noise when i backed off the accelerator at motorway speed. I checked the half-shafts and UJ's as well as anything else i could think of, but found nothing. I was concerned that i would brake something if i drove it, so i kept it off the road, until last week when i took it to a garage for a new xmember and an MOT. I asked them to have a look for the source of the noise but they said couldn't find anything obvious either, and suggested i 'let the problem develop'. Since then i have driven about 200 miles and, sure enough, the problem has developed and it's now grumbling from about 35mph and get's louder the faster you go (Noise still only happens when you take your foot of the accelerator). It has also become accompanied by a wonky rear axle, which i didn't have before i took it to the garage. Could the noise be related to the axle not being straight?
Also appeared is a clunk from under the vehicle when i start the engine. It happens when the tf box is in neutral as well as in gear with the clutch in.
The vehicle is supposed to be for our honeymoon- to take us round europe, but it's at close risk of running over budget, so all help would be massively appreciated.

Cheers,
Steve

Check for play in the propshaft UJ, and check the rear radius arm bushes and the Aframe ball joint.

i agree with redhand

Rear radius arms (straight) and their bushes,
Chassis mounts where the above attach to,
Axle mounts where the above mounts to,
A Frame ball joint,
UJ's,
check oil in diff check diff input flange for tighhtness its not uncommon to come loose.

Thanks a lot, i'll get onto those now and see what i find.
Cheers

Right, i'm back and, after some kicking and swearing, i'm none the wiser. I've checked everything you mentioned, aside from the diff input flange, as i'm not 100% sure how to- but i can't find any play where the prop meets the diff.
The a-frame chassis mounts look like the metal moth has had a picnic- they're pretty crumbly, but the ball joint seems fine, as do the radius arms, although the bushes are looking a little tired- but still have some bounce. The radius arm chassis mounts look rusty, but they seem solid. The UJ's are fine- there's no play in them, and the rear UJ was replaced quite recently. I also jacked up the vehicle so the rear wheels were off the ground and tried yanking the axel by hand, but couldn't. I also took some photos, so i'll upload those in a moment or two, when i find my cable.
Could the misalignment of the axel be related to the grumbling noise do you think?
Thanks again