"I think you'll find the FDR is located on most modern aircraft behind the pressure bulkhead, never yet seen one on the vertical fin, but am willing to accept that some may have it there"
Don't you mean in front of the rear pressure bulkhead? If behind the bulkhead or on the top of the tail, then an Airbus is indeed a strange bird... and nothing like any of the Boeings and MD's I've worked on (and changed DFDR's or CVR's on). I am more inclined to believe that these boxes will be warm and cosy somewhere inside a pressurized area.
If you need to know exactly where it is, post this question on the Tech Log or Engineers forums on this site
Q.