Found it behind the climate control module.

 

Dunno about the connector. Show the front side of it.
Just curious... Why do you have 2 antennae cables?

 

It's factory wrapped in that sponge-y stuff, so I'm going to leave it... but I think it's for the analog climate control that came with some D2s maybe? No idea.

And not sure why the two antennae cables. They both have spots to dock into on the factory Alpine headunit though ¯\_(ツ)_/¯

 

i believe that one antenna is am and the other is fm. the rave explains all of this. there are two antennae embedded in the rearmost windows, one on each side of the vehicle.

 

Some models had the "diversity antenna" option mollusc mentions, and others had the second wire for the onboard NAV system option that had a scrolling text display in the head unit. My S model has just one wire but the second antenna is in the back drivers side window with no amp or wire in the headliner... So S models got a single window antenna for both AM and FM. Also there are blue and green RF amp modules, one for FM only, the other for AM/FM.

 

There are a number of connectors that act as intermediate distribution blocks in the wiring harness. Based on the color of the wires going into that, I would say that is one of those.

 

The electrical manual says something to the effect of high end (Harmon Kardon) audio systems have 2 antennas embedded in the rear glass, one is an AM/FM antenna and the other is just an FM antenna to "improve reception in urban environments."