Td4 knocking even after new rear diff fitted!

Dear all,

I have a 2001 freelander td4, about 6 months ago a slight knocking started at the rear only when turning right or left... It has got a lot worse ! You can slightly hear it going straight but when on full lock it's a thudding, I had the rear diff replaced yesterday... No change at all the front diff mount was replaced about a month ago as an mot failure the other mounts seem fine ..... As you can only hear the noise on load my mechanic is also stumped.....
Any ideas ?

Did yu not check chassis for cracks and subframe mounts first?

There are no visible cracks on the chasis or subframe mounts, the prop seems ok driveshafts are fine... can't produce the noise unless its under load.. the noise is exactly the same turning either direction..