I'll admit there is some of the way police units were ordered (as police units), there were many variables in how they ultimately happened. I suspect there was a "minimum order" in the number of units which the local dealer could submit to Chrysler for "bid assistance pricing".
At the municipal level, the locals formulated the bid specs (i.e., vehicle wheelbase, engine size, transmission, axle ratio, related equipment). Of course, the specs would need to be generic enough to cover several brands of vehicles (typically Plymouth/Dodge, Ford, and Chevy). BUT they might formulate the bid specs to favor a certain brand of vehicle over another, if desired. They couldn't show overt desires, but if you read the bid specs (as written), you could sometimes see what they might want. Although these specs would be open to any dealership, some might choose not to bid.
OR, if they couldn't afford a "real" police car, or didn't feel they needed all of the HD components, they could spec a normal car with some HD options and rely upon local vendors to install any additional equipment. The Chrysler HD Trailer Package tended to mimic some of the police equipment, but without the police-specific wiring and such. And, if they had a good used car lot dealer association, they could purchase a "used car" and then convert it to police uses. For example, they could possibly get a local dealer to order in a car as they desired, equipment-wise, put it in "demo service" for several thousand miles, then sell it as a "used car" to the municipality. This might be an option IF the price of the used car was under the stated amount of money where actually letting bids was necessary (a local municipality determination, usually).
As always, the "real" measure of a genuine police unit, is the Certified Speedometer in the instrument cluster . . . other than VIN-specific characters. "Special Mask" would probably be for state units, unless the local bid was in a generic configuration and color scheme, I suspect. IF the certified speedometer is "there", the rest should fall into place, I suspect.
CBODY67