Outer Limits 4x4 Board

I'm getting a clicking noise from the rear diff, most notably when moving slowly, 1st and 2nd gear, in Fwd and rev. It is heard when decelrating weather clutch is in of not. Seems to be getting worse, any idea's??? I've checked the oil level.

Simple cheap things first.
Have a close look at the rear uni joint of the drive shaft, any play, grease pissing out etc?
Same for the CV joint in the middle of the drive shaft.
Rear wheel bearings, when where they last serviced?
Rear brakes, pop the drums off and have a good look around, nothing loose /catching? shoes still have lineing?
While youve got the brakes drum off push/pull the axle, any play? more than a couple of mm? Think about replaceing the rear wheel bearings.

No luck with any of the above?
Remove the axles, while theyre out you may as well replace the rear wheel bearings, change the races as well as the bearing.
All the splines still on the axles? no obvious twists,cracks,bits missing?
Pull the diff centre, undo all the bolts and nuts around the centre, with the axles out, the drive shaft disconnected and a bit of persuasion with a dead blow hammer it comes out fairley easily, weighs about 10 kg so dont drop it on anything.
Have a good look at the teeth on the pinion gear(the small gear) and the crown wheel, any missing/chipped teeth? check the pinion bearing for wear /damage, if the pinion moves in /out more than a mm or so or it feels notchy when you turn it the bearing may need readjusting or replaceing, does anything click when you turn it?
have fun.

Well found out it wasn't the diff but the leaf springs on the right handside. As the diff twisted it made the top spring clap against the one below it..