It's unlikely it's a Savoy. Most likely a fleet special. There are fleet special ads and police brochures for the 62 Plymouths on eBay regularly.

If you can figure out where it was originally in service, there is a small chance they have more info on the cars put into service that year.

One pointer to me was to check the glove box for a speedometer certification (Michigan State Police apparently certified the already certified equipment a on their cars) for the unit or location it was assigned to. Also specific number assigned to the car by the department is sometimes written on the inside of the A-pillar.