1999 a4 avant radio issues
 

After almost 20 years the radio and antenna have decided to quit cooperating- the cassette player has eaten my last tape and won't eject it, the oem CD player keeps stopping so it it's out with the old and in with something else- an Eclipse am/fm/cd my wife gave me a while back.
I've figured out the power hookup and the front speaker hookup using adapter plugs but is there an adapter to plug into left over plugs to get the rear speakers working? This appears to be a perennial question.
Thanks
Mm