Very rusty rear axle on Ford transit

[bongoboy]

I have seen a nice Ford transit van that i'm thinking of buying.
The only fault i can find (if you can call it that) is that it has a very rusty rear axle, the rust is on the middle casing where the oil goes.
I know they can get rusty as they are underneath and exposed to the elements, but this ones very rusty.
Is this a concern or would it cause no problems as i assume the axle is thick heavy metal and therefore the rust would only affect the casing surface.

[AlBags]

approx 1.6- 2mm steel plate for cover and casting on body.
I have only ever see one start to leak because of rust pitting.
My guess is that it looks worse than it really is.

[mdoo98]

A good coat of Hammerite would see to it

[bongoboy]

thanks very much for all your answers