Help with a bizzare '86 SSP - Texas car (not necessarily DPS)

[ChrisL]

This car has come up before, maybe 6 years ago or so on other boards. It's an '86 SSP, with a 57 (houston) DSO (special order 0029).

So the first buck tag reads:
DSO 57 - 0029 Texas
Special Service Package

Door tag and secondary buck tag info go on to show a 5 speed car, 3.08 gear with A/C but the peculiar part is that it was ordered in 1E silver with the charcoal VINYL interior. The car was apparently first registered out of service in Fredericksburg,TX in 1992 and since then it has changed hands a few times. It falls in a batch of 5 consecutive VINs.

So, the question is, any idea what department might have ordered this car? The batch of 5 seems a bit small for DPS, and the combination definitely doesn't fit with DPS. DPS always ordered cloth interiors (I would assume a vinyl interior isn't much fun for an officer who spends all of their time sitting on it) and obviously the color doesn't fit for what DPS typically ordered.

Any ideas?