You could get a rear part, but you'll need to cut the old one off, as it's one piece from the factory (I think!).
The middle silencer section is £160, the clamp is £15 and the back box is £271, so you're looking at around £450, which could buy you a VERY nice stainless custom system, with change left over.
OK, so you wouldn't be able to get your hands dirty, but the longevity, sound and fit/finish will be worth it.
Cheers,
Mike