I've seen plenty of plain clothes AHB M-bodies over the years, never badged, which still had the 318-4bbl.
I've also seen AHB tagged M-bodies with slants and 318-2bbl's. Those were badged and wearing municipal colors.
The cars were ordered in batches and assigned duties from there for the larger orders. Smaller municipalities usually piggy-backed a car on larger state orders to be able to get the better buy-in.