I put some "want ads" out on various craigslists looking for info about SSPs that might still be on the road today. Got a hit on a 1986 FBI unit!
Somebody that knew of the car, who also purportedly is a multi-SSP owner, sent me a pic of the lower left corner of the window sticker and told a previous owner of the car about the ad I put up. The previous owner contacted me and gave me his phone number so I called him and chatted a bit. He sold it a couple of years ago, and still keeps in contact with the current owner. Hopefully I can get some more info on it.
Bill put up a page for the car here:
http://www.specialservicemustang.net...info267059.htm