The Ford Ranger is a 4x4 vehicle, used in a variety of policing and emergency roles. It's used by all emergency services: police, fire, ambulance, and rescue associations - anywhere where the 4x4 capabilities are necessary. The Blaine County Police and North Yankton Police are rural policing forces, that often deal with incidents off the road. The Coastguard and Rescue Association often work on beaches / off road, and the fire and ambulance specialist teams also need to make use of the 4x4 drive.
In my videos, the Ford Ranger I use is the 2014 Ford Ranger ELS model by BritishGamer88. Unfortunately, this mod is no longer available online. You can see all the mods I use in GTA 5 at the modlist page.
Here's a look at the different liveries of the various police forces using the Ford Ranger: