If you mean play in the flange you need a new bearing. There should be NO play in ANY direction, in or out, up or down, side to side, on the output flange. You may have some rotational play on a well worn diff however. You would normally fit a flange and seal kit. Around £25.00 look around the spares sites.
There is round play where the prop disapears into the diff and rotational spatter around the body in a line, don't know if there is a seal that has gone or not
The oil seal has gone if you only have rotational play that is ok. You could try an oil seal alone but it's more usual to fit a flange and seal kit these days. This Diff Flange & Seal Kit (OEM) STC3124G Island 4x4 - Specialists in Land Rover and Range Rover Parts and accessories for all models. UK and worldwide mail order. but if you look down list flange seal is there at £5.00 plus vat.
