leaking disco rear axle

i noticed the other day my rear axle was low on oil so i topped it up went for a spin when i got back i happened to look under the ass end an noticed spots off oil everywhere its when i noticed the rear diff was leaking not sure where its coming from goin look tommorrow anyways i was wondering if its the black plate( if thats what its called the oval cover on the back off the diff) if it has a crack in it could it be weilded up? all help is welcome
ok looked at it now an it appears there are 2 small holes at the top off the back pan i have used some eproxy stuff as a tempery measure till i get get it booked in.
ay ideas what will need to be done? can u fit a new back pan?

mine had rusted, so been coated in sillicoon,
lets see you leak through that ha