Today I bumbled around enough to get my 2005 AX back on line for AirPlay.
I eventually did a full reset and then found it on my iPad. Downloaded the Airport Utility for iPad which then ionformed me it couldn't set up my old AX.
Went to my iMac and opened Airport Utility on it. It didn't show the AX either. I finally looked under the Airport icon and way down near the bottom was listed the AX. Clicked on it and Airport Utility told me I needed to download Airport UItility 5.6 (for Lion) which I did. Installed it and could finally set up my AX.
Meanwhile I also downloaded a firmware update for AX not knowing if I needed it or not.
I spent several hours fruitlessly searching Apple Support for the necessary info before I finally found the solution.