ksbkrew, did you get this replaced ok in the end?
Chris, when you say it's structural, I take it you mean from just the point of view of supporting the radiator?
The centre part of mine is starting to go (no where near approaching the radiator falling out, fortunately) and I'm thinking about welding a bit of fabricated sheet steel in to replace the rusting part - or even getting a decent section out of a scrapper and replacing the whole of the middle part, rather than trying to get the whole lot changed. It seems an easier solution - at least to me.
Believe it or not, buying the new SMIC off you started this little project. Thought I'd replace the aircon condenser at the same time, only to find out that the radiator didn't look too clever. Then I discovered the rusty cross member...