Ah, that sounds like the unit empeg did for Visteon - there was a picture of it on the Visteon web site (actually think I still have a copy somewhere myself). From the outside it looked just like a MK1 with a blanking panel on the front instead of the display, and it pretended to be a CD changer so it could be operated from a standard radio with changer interface.

(list 6284, Mk1 S/N 00299 4GB blue [for sale]. Mk2 S/N 080000094 6GB blue)