can anybody tell me how to remove the rear diff as i dont wanna do it wrong!
thanks

Simple instructions is keep unbolting stuff until it comes off.

The only special tools you will need is a good 1/2" drive allen key drive set. All the bolts will be tight and hard to remove, so clean out all the allen recesses, and make sure the allen key is a tight fit and properly in.

1. Jack up rear and support on axle stands as high as you can get it, remove exhaust from back of mid silencer
2. Remove CV joint bolts at diff and tie them up. Drain the diff oil, possibly by removing the rear cover or use the drain bolt if its there.
3. loosen accessible diff-5th gear housing bolts
3. remove the 2 bushes holding up the diff and support gearbox with with trolley jack
4. Un-bolt remaining gearbox bolts joining the diff and lower until it will clear the de-dion axle. The bonnet should be open as the engine will poke up at the front. You may also need to free up the gearstick, but you should be able to just remove the leather and rubber parts from the inside, to allow it to slide down more easily (its mounted on the torque tube).
5. Slide the diff off, it can be hard so preferably with 2 people, it may require some shaking. Watch out for the shims and the drive sleeve, as these need to go back in, and be careful not to damage the sealing face.

For reassembly you will need a new rigid diff-gearbox gasket from Volvo to ensure the bearing clearance remain the same otherwise you will get whining. I think this is one of the ones still available, the rear diff seal is not so see the gasket thread for a source if you need this.