Ok, I confirmed this morning with the CTSP that they
do not title their cars until they are done with them - a manufacturers certificate of origin is the only documentation until the unit is auctioned off. Again, confirming the obvious that this is not a CTSP car. Also, the Mustangs that were purchased were in various colors of Red, Silver, Blue but no Black so that the car would retain a higher resale value at auction, along with the obvious stealthy attributes of a multi colored fleet for traffic enforcement.
Now, with the grease pen markings in the engine compartment, it could be from a municipal fleet garage. So there is a potential that it was an extra from the batch of 49 that were built with the Detroit (48) DSO in 1989 and was used for a fill in for something else in a local fleet.
Interesting "mystery of history"... but it doesn't seem to matter about some of the facts for eBayers these days.