The main issues with these are electrical. Make sure they didn't just cut out the old wires when they were removing the systems from the car to be sold. Also Chrysler products on their own have issues with electronics.

Make sure it gets inspected by a mechanic or bring a mechanic with you to get it inspected before buying.

Sometimes these get driven into water at high speeds and make even more problems.

Personally, they are run hard (not floored but a lot of idling, shifting, etc) and put up wet.  I would look at model you want that WASN'T a police car.

And deal with communications later... they're just electrical addon on's.

So, you are former law enforcement. You probably know that idle hours are a big deal on patrol vehicles.

The Chargers have weak spots in the engine (oil leaks on the Pentastars) and serious coolant problems (Pentastars again).

If you are looking for an Interceptor to use, I would get a P71 Crown Vic. P71's were the pursuit units and you can typically find them with decent idle hours on the clock. Taken care of, they can run FOR...EVER. Fun fact: a lot of them are retired from service at 150k, then sent to New York to be taxis where they go upwards of a million miles in the harshest conditions. The P71 package beefs up the tranny and cooling systems to deal with extra stress, and also gets heavy duty shocks and brakes. 

Look around and you can land a clean one in the $5k range. A Dodge Charger Interceptor is a bad move. I have immediate family in law enforcement and get to see how those things just do not hold up.

Crown Victoria. The standard in law enforcement for years. Acres of room. Civilian model that wasn't run hard or idled 7 days a week.