I see you've dug up one of your old articles on this from Spaceflight magazine. I don't want to tread on your toes so I leave it up to you as to if you post it here.
Here's the article from 1998.
A few notes about this subject:
-there is still some disagreement about what the QUASAR was derived from, and also if there was a different set of SDS satellites before these block 2s. I am reasonably confident in my analysis in the TSR article. But it's not 100% confirmed.
-I've been working with a couple of people establishing a chronology and we are pretty confident that the satellite seen in the photos is almost certainly the one that is now left over. The satellite was filmed in the late stages of construction in December 1997 (aired on CBS in February 1998). There was an SDS/QUASAR launch in January 1998. It seems highly unlikely that they finished the satellite, tested it, shipped it to the Cape, and launched it all in under two months. And there is reason to believe that no more of this type were launched after January 1998. Hence, it is left over and now being offered to NASA.