Another problem!

I was taking off the exhaust box when I noticed a hole in the rear axle. Its under where the shafts go to the left of the diff. The whole area looks as though its pretty rotten. Is this dangerous?? Another thing to try and source in the US, as well as a petrol tank, front driveshafts, ....................

I envy those of you in UK where you can find all the second hand parts within 10 miles of your house.