I have just come across this thread and I have found new developments with that Silverliner II.
While riding by Wayne Electric today, 7/19, I noticed that Silverliner II coupled up to a Silverliner IV single unit in the yard. What I found even more crazy was one of the red lights on the SL-II was lit up! The pan was dropped on the SL-II and was up on the SL-IV. It looked very clean, too. I didn't notice any rust, graffiti or anything. All of the decals around the windows and the SEPTA logos on the ends were very much in tact. The number boards were gone, just like what's pictured. It even looked like the headlights lights were still in below the cab windows, which I believe are missing from that heavily tagged Airport SL-III and SL-II coupled up to it.
Speaking of the SL-III/II, I have noticed that people were saying that the SL-II mentioned above is the SL-II that has been sitting behind Wayne Electric for the past 5 or so years, however I think this is a different one. Number 1: the SL-II that has been sitting with the Airport SL-III was still visible today, still in the same spot as they have been. And number 2: the pan looks like it is relatively new. It's silver, unlike the two sitting Silverliners, whose pantographs look quite dirty and are red.
On the return 3 hours later, the SL-II and SL-IV single were both gone from the yard. Some Bombardiers and Diesels and other un-retired Silverliners blocked my view of the Airport III and SL-II, but I'm pretty sure they didn't move those.