Yeesh. I remember the cuss-fest that was the replacement of the factory shaft style head on my '83. Laying on my head under the dash trying to trace wires and getting the mounting level. Both my front speakers have stopped working over the years, but with the line-X only interior and loud exhaust, the sound quality is so bad, I seldom even care to try listening to the radio anymore.
Somewhere along the line I ran a mini-plug cable out from behind the unit so I could plug in my phone and listen that way. Funny thing is, my 2011 Jeep has essentially the same setup, except the wire plugs into the front of the unit.
They have devices that listen on bluetooth and broadcast on FM, so you can just tune your radio to a particular channel and listen to your phone or tablet that way. Could be slick, but I haven't tried it.