Seattle Lion - The block heater was an option (which I ordered) on my 2013 F350.
If installed, there will be a short 110 volt cord coiled up that you can see hanging down just to the left of the front license plate holder (standing in front of the truck). It is all black and has a black cover over the plug end so it is a little difficult to see.
But - It may be standard on trucks that are ordered from dealers in northern states. Best idea is to call your local dealer and ask. I would guess it would also be listed on the window sticker also.
Tim B.