noise on overun

I have a defender 90 done around 160.000 it's started to make a growling noise when I take my foot off the gas then goes quiet once slowing down on the gears starting get really loud now.
There is a bit of play in the rear diff and a bit in the gearbox I don't think there's enough to cause this much noise and I can't decide were exactly the noise is coming from.
Any ideas most appreciated Eric

Have you checked the exhaust is secure and all rubber mounts are intact (give it a good push / pull) and not close to other bits? Sometimes exhausts can touch frame rails etc and cause noise at certain revs or power on/off depending on how the engine moves on its mounts.

Exhaust touching chassis rail can make a growling noise.

Normally if all else is sound, overrun noise would be worn diff pinion bearings. This occurs when the crown wheel is driving the pinion on overrun and the pinion changes angle. Noise reduces on acceleration but returns when throttle is lifted.

It's mostly been said above, but very often it's an amalgam of lots of little things just wearing .. fix one thing the noise changes, fix another the noise lessens, fix something else it might go away. Occasionally it's just one thing, maybe any of the above, maybe a worn UJ for instance. So many possibilities!

Mine made a similar noise when I first got it.

Checked it over and could not find anything loose or worn,gave the UJ's a good greasing as part of the maintenance and it stopped.

Cheers

Thanks for the reply's having already checked for loose fittings etc the possible cause could well be as wammers said so as the propshaft is new I will try and shim the diff and see if that helps.
Many thanks Wammers and to all others