yeah sure you can run it. its only different in color. first offense getting caught is 5000 dollars, or $10 per gallon, which ever is higher. a nice way would be to have a off road tank of 90-100 gallons that hides between yourbed and toolbox, (like in northern tool catalog) and then fill your tank up with 10 gallons (tank that came in the truck) of on road diesel as a deterrent. make it look legit, with a pump and hose on the tank ("off road diesel only" sticker) . but instead of using the hose and all, just adapt it so that the truck will pull fuel from the off road tank. then stop to fill up your off road diesel tank with fuel, and then that way it would be much harder to get caught. if a cop dipped the tank (the 40 gal tank) it would look like you have 1/4 tank of fuel left. good idea?