Healy,

Did you buy it with a RWC? Cause that ain't roadworthy as it is

A bit of a tough repair, but there are guys that can fix stuff like this and plenty of other people have had chassis repairs done from torn, cracked or broken rails.

You would have to cut, insert a sleeve or fishplates, and reweld a good rear end. Not sure how that will go legally though, as i don't think they allow cut and shuts anymore.