Hi John
Apologies for leading you astray, memory is not what it was once!
As kelvo says the bord monitor screen is driven by the TV tuner and to have it to display correctly you'll also need a BMW widescreen TV tuner such as this
https://www.ebay.co.uk/itm/BMW-E46-E...frcectupt=true
There's several currently on eBay just make sure you search for "BMW widescreen TV tuner".
I fitted a BMW hybrid analogue/digital TV tuner when I upgraded, can't see any available on eBay at the moment though this company do digital upgrades to analogue units
https://www.ebay.co.uk/itm/BMW-Range...53.m1438.l2649
As you've the CD version of the board monitor and a BM54 are you thinking of adding the bluetooth phone function, if so you'll also need a BMW ULF control unit and fabricate a harness for it.
Jim