There are more issues than just the datalink question. Cosmetically the BG9500 & the BG4500 are the only 2 beograms with the mirrored panels on sloping lids. However the 4500 has a RIAA (pre amp) fitted and this will require disconnecting before using with your beocenter unless you connect via the Aux input which will mean no remote control functions. This is due to your beocenter also having RIAA fitted on the phono stage which is the correct input for beograms. The BG9500 of course is the deck which was released to match your beocenter - hence the cosmetic match & no RIAA fitted. (The BG4500 tends to command a high price as do all of the Beograms with RIAA installed).
Assuming you are looking for one of the later generation tangential tracking decks.
If the mirrored panel isn't too important then the BG3000 & BG3300 are basically identical to the BG9500 and have at least aluminium panels and the sloping lid. These are widely available and normally fairly cheap to buy and will work well. The BG8500 is also the same basic deck with the sloping lid but this has a matt grey finish. Any of these plug straight in and work, along with Beogram 5005,5500 & 9000 all of which have square flat lids and not as good a cosmetic match. Of course you could obtain ANY of these and replace the lid at some point with one from either a BG4500 or 9500 - there's one for sale on ebay.uk at the moment but they rarely come up for sale.
Hope this helps in some way.
Chris.
The use of metaphors should be avoided like the plague. They're like a red rag to a bull to me.