Thank Bernie!
Jim, your care-package arrived safely in the mail. There are A LOT of pages to be organized and scanned. It is going to take weeks for me to get all of this done.
To give you all a taste, there is a CHP document for the 1989 Mustangs which lists the unit numbers and VINs. The interesting part is that it identifies a stand-alone VIN, followed by the group of cars ordered consecutively (but the VINs are jumbled because they are listed by Unit Number). We know that the CHP would typically order a single Mustang to check that the equipment upfitting would work in the new model-year car. With this paperwork provided by Jim Young, we now know that the single 1989 SSP initially checked by the CHP was:
http://www.specialservicemustang.net...info201827.htm
How cool is that?