Defender rear diff issue

Looking for some help
My defender rear axle ( i am assuming ) makes a bad grinding noise when you back off accelerater I have recently replace the uj's on the prop shaft so I have removed the diff for closer inspection now all lookes good no damage or bearing issues that are obvious appart from one cog in the diff that has some movement in it see pics is this normal or is this my problem ?

noise when lifting off the accelerator would likely be a pinion bearing, not your diff gears

There no obvious play in any of the bearings assuming I would be able to feel play or would i need to dismantle to ?

you should feel it but you may need to take a look

Transfer box output bearings? Noises tend to travel unfortunately.

another thing to check is that prop slide does slide