Rear Axle problem

I have a 1993 3L Diesel, 4 WD, supercustom. The rear axle started making a whining noise. I refilled with Oil. On the test run the noise came back very soon and the oil was leaking. My local garage took one look at the leaking oil and said I needed to replace the axle. It is proving difficult to find a replacement axle - I am in England, near Bristol. My questions are: Do you agree that the only solution is a replacement axle? Any ideas how I could find one and how do I check it is suitable?
Any advice appreciated - Thanks, John

WHERE exactly is the oil leaking from?

I think you would have to strip down the axle, and replace all the bearings and seals an get the diff setup again..Thats as longs as the diff gears are ok... Its a job for a more experienced Mechanic and Replacing the axle may be easier. If you can find one.
Unless the oil is leaking form left or right side, maybe try jacking that side up and spinning the wheel and see if its noisy as it may be just a bearing and seal replacement, your mechanic should be capable of that..
If it diff seal leaking and the diff bearing are worn, its a more complicated job..
That said , i have never done a Hiace axle but done plenty others.

Thanks GPW and richturn. I will check to see where the oil is leaking.