Guys - sorry for delay in response but I work away quite a bit.
I checked the link above in my second post and this should take you to the exact place I bought mine.
It is the Alfa 166 / Lancia Lybra modified Becker unit.
It's an OEM kit so comes with brackets, screws , earth strap - everything except instructions !
The unit mounts above the battery which should be in nearside of boot. The cables apparently should always already be there - but neatly tucked away underneath the battery support plate.
Becker 12v Silverstone BE2660
CD Changer for Alfa Romeo 166 and Lancia Lybra.
I ordered this as a specific OEM 166 unit not just as a Becker Silverstone 2660 because I could not be completely sure the standard unit is exactly the same and if there were any mods added to talk to the Siemens ICS.
The one thing you do not get with the kit is the nicely finished carpetted box which goes around the Cd changer, Nav etc. and sits on top of the battery to finish this off.
I was quite happy to fit the changer and then tailor some MDF to fit with acoustic cloth used to match the carpetting.
Please note the interior boot trim is very simple to remove and put back, the battery is easy to remove as well as the base plate but heavy.
Do make sure you have your ICS code to reactivate the system once the battery is reconnected.
The kit contains two types of mounting brackets to enable upright or horizontal mounting. Standard mounting is horizontal and should be intuitive.
If you want extra advice please let me know - if the going gets tough I could take mine out and take some digi pictures to illustrate.