(pictures from flickr
http://www.flickr.com/photos/67284583@N08/)
Here are two other pictures showing a little bit more detail (or at least what can be seen).
Few things that point out this isn't a Police Patrol...
The flat firewall.
No cowl lights.
The back edge of the door curves towards the front of the car, the Police Patrols had a vertical line.
Also, the "M" license plate on the vehicle is incorrect. "M" plates started being used to signify "Municipal" plates in IL back in 1939/1940. From 1929 until 1939 "M" plates were used to signify the smallest weight class of trucks.
Still pretty cool looking though!
-Tim