I became a fan of Plymouth GTXs and Dodge R/Ts when I reached driving age, knowing they were powered by the identical engine used by the PA state police in their full size Fury II's. Even in the full size cars, they had the same unbeatable exhaust sound. I always assumed cost was a factor in the fleet choice, but I wonder if Chrysler was able to bid more competitively because of the sheer volume of sales to state police fleets around the country. The reliability of the high performance 440 may have entered into the equation as well.
The local municipality, on the other hand, ran Chevy Bel Airs, with 350s. Maybe they were cheaper in lower volume purchases. Then, in 1972, the town upgraded to Plymouths, with same package used by the State Police fleet. Within months, there was a crashed one sitting at the dealership every time my dad took his Valiant in for servicing. Mismatch of high performance cars with lower performance drivers. The town fathers went back to Chevy the following year.