thanks everyone.
The axle in question is 5 bolt and I'd describe it just the way that In2Deep describes his (breather hole etc.) And after measuring it last night it is definitly 2.25 inches too narrow.
I had not thought of wheel spacers as I'd never heard of them. Can you advise if these are common items and where I might get a pair? - sounds a lot easier than getting a new rear end.
