Hello My Fellow Aurora Driver.
To replace the atenna is easy, Its loacted as you know in the right rear wheel well part of the trunk.
There is the cover that removes 2or three hand screw plastic bolts and the cover comes off.
The atennia has 2 or 3 bolts that you need to unscrew.
Then there is the trunk cap, that is the little hole where the atennia pushes out., There is not need to unplug the battery.
You need to unscrew that from inside.
The arennia job should take about a half hour.
If that one from the junk yard does not work, there is always some one selling parts on Ebay for your Aurora.
Good Luck.