Looks like a Denison iPod aftermarket unit to me. I had one in my ford fiesta a few years ago before I upgraded to an Audi. Mine had the exact cradle and the unit was connected in via a FM modulator. It then tuned into a free radio frequency. If I can remember it was something like 88ish FM don't quote me on it. The way to tell is to plug the iPod in and play a song and just scan the fm radio channels and it will hopefully pick up the right frequency.
This is just a suggestion I carn't tell what the connection is but as stated earlier if you follow the wiring you can tell how it's wired up.if it is an fm modulator then it will be connected to the car arial
If it is a FM modulator there are far superior ways of attaching an iPod to the head unit.
When I plug in the iphone the head unit starts to beep intermittently, and keeps beeping. I can't get it to play using any functions on the stereo. I have the Bose setup.
I need to find where the wires go, but it's a tidy install and they appear to tuck straight up the mounting bracket out of the top of the glove box.
I will give the FM a go later, but due to the stereo beeping I guess it's plumbed in somewhere. I reckon it's for older i-devices.