There are many threads on this subject throughout the forum.
Having read them all I am nearer to finding the answer I need.
A question I have though is that I have to replace the front mounting on the rear subframe. I have seen various documents quoting the bravo bush as an alternative with slight modification.
I have also read about a vectra bush but can't find confirmation in any of the threads as to whether the vectra one is for the front or the rear mounting.
If anyone could confirm then that would be great.

Hi,

not sure about the vectra route but i posted about the brava bush and it worked for me it's still in there! only very slight modification to rear subframe to get it to fit and at the end of the day it's a fiat bush thats in there not a GM one!

After trying a few suppliers and getting nowhere I found a guy selling the brava bush on ebay at £89.99 for 2.
Seems a bit steep to me so I lowered the front of the subframe and packed it up with a doughnut shaped piece I cut out of an old tyre.
Clunking has stopped, only question is how long it will last.
The tyre was free off my friendly local scrap man and the job took me about half an hour.
I will update this thread when it starts clunking again, see how long it lasts.