Thanks Mike, pity I didn't know or realise this before removing the diff flange. Although, the seal needed doing.
I think I will have to drain oil, as I would replace the seal, seeing as I am taking off the flange. Saves me having to do it at a later stage.
Would this be the correct part to get, that would fit the large end of the propshaft?
http://www.brit-car.co.uk/product.php/408398/2720/transfer_box_fr_flange_kit_disc11