Make sure you use either an electric gauge or a mechanical with a pressure isolater.
A pressure isolater mounts in the engine compartment. Fuel presure pushes on one side of a diaphram. The diaphram then exerts pressure on the other side which you fill with antifreeze. The pressure line filled with antifreeze goes to your mechanical gauge in the cab. So if you ever spring a leak in the cab, what comes out is antifreeze and not flamable fuel.