How to check / inspect a diff!

Hi,

Got a 200tdi defender fitted with a disco1 rear axle.

Been getting quite a lot of knocking on gear change and particularly when setting off in 1st.

I know there is play in the bearing at the input to the rear diff, cos I can move it up and down by hand.
I've removed the Diff and want to know if there is a way of checking them?
I don't want to replace the bearing to then find the whole thing is still knackered when I put it back.

Any ideas???

Btw it's a 24 spline but I guess that doesn't make much difference.

Steve

A good visual examination of all the gear faces for chips / deterioration is a good start. Also check that the diff gear splines aren't worn (check with known good halfshaft). If all that is ok then its just down to bearings and seals. Be aware that you can't just replace the bearings, they need to be set at the correct preload and backlash. Plenty of info on here and on the tube.