David,
Sorry to hear that JB didn't have any bits for you.
I found another link in the States who charge $1,800 for a rebuilt axle but don't seem to have any other spare bits in stock at present.
http://www.morgan-spares.com/plusfour/rearaxle.htmlI guess the perfect solution would be a written off car or one that had rotted out, not very likely I guess where you are.
It must have had a major happening to create that much damage to the axle at some stage.
Good hunting.