I gotta believe that each Ram fob is unique to the truck. If it wasn't, any fob could open any truck, and "away we go". That being said, if you buy a new fob off of e-bay, does it have to be programmed by the dealer to your particular VIN?
I can't start my 10' without the fob. I can get into the truck with the emergency key, but I don't believe it will start the truck.