Stereo for Euro model

[mavnick]

I have a 1986 325e euro. The previous owner had removed the stereo and the only wires coming out of the gap are the antenna wire and a seven pin male round DIN plug.
I've taken it to several stereo shops and what they want to do a complete rewire job. Someone else told me that it was probably for a cd changer. In either case there does not seem to be another harness anywhere in sight. Anybody else ever come across this?
Thanks

[Matto]

I know I have that din plug for my cd changer in by 325i. the rest tof the wiring for my stereo is just loose wires all color coded.