Hi MarkSYD, greetings from Castle Hill!
Well actually Canberra, the car's in Castle Hill.
It looks like you can replace the window if you wish, see the following threads/posts (unfortunately the pics have gone AWOL):
[url=http://club323f.com/forum/viewtopic.php?f=18&t=56712&p=724284&hilit=rear+window+replacement#p724284]Post 1[/url]
[url=http://club323f.com/forum/viewtopic.php?f=14&t=52957&p=717952&hilit=rear+window+replacement#p717952]Post 2[/url]
Alternatively you could have a look under the trim on the rear hatch- it may be that the hatch has its own wiring loom and there are connectors for the car's loom just inside the top panel of the hatch- apparently there's a connector there for the high mount rear stop LED/light. If this is the case you can simply unplug your car's loom swap the hatch over and reconnect the car and hatch looms.
Good luck, let us know how it goes,
[b]Patrick[/b]