Have a carfax or similar report run. I'm not sure what an "EB" is, so I can't give you any hints. I know, for example, Ford Crown Victorias have a little plate on the trunk lid which reads "Police Interceptor", which is a dead giveaway.
Look at the doors at an angle for telltale signs that there might have been a police decal on the doors at one time (bright paint surrounded by faded paint).
