Aaron,
I think Marco was quoting you new prices from Bara which included the 3.64 CWP? These are expensive and rare, but if Tim has a 3.64 CWP 9" for £2.5k, bite his arm off . However, I suspect these are more likely to be 4.4s and are absolutely of no use to you what-so-ever. Be careful as even if it does seem a bargain, some of the early 9" diffs cannot even be converted to run a 3.64 CWP, so you could end up buying an expensive ornament .