When a diesel starts running away, depending on whether it's running on fuel or oil, there is one basic and sure-fire way to kill it. Cut off it's air supply. No fuel, be it diesel, oil, trans fluid, whatever- can burn without air. On all the refinery trucks now they have a butterfly valve plumbed into the intake, and a sensor to detect high levels of hydrocarbons in the air. That way if there is a major gas or fuel leak at the refinery, the diesel engines won't run away, blow up, and cause an explosion. I watched a generator service tech save a run away cummins generator once by dumping a full CO2 fire extinguisher into the intake. Fuel needs oxygen to burn, so cut off the oxygen and the engine will stop.
For peace of mind it wouldn't be that hard to rig up a CO2 fire extinguisher in the cab of the truck, and have it plumbed out to the intake. If the biscuits hit the fan you can reach down, pull the pin and push the lever down and dump a bunch of non-combustible gas down the beast's throat.
That is, if you've got your wits about you... Me personally, I would probably be in "my happy place" and getting my thoughts in order and confessing my sins...