Chances are if your truck died going down the road it is your Cam/Crank position sensor. If it turns over fine and does everything normal accept for starting thats your problem. That sensor tells the computer where the motor is rotation wise and if it goes dead the truck wont know when to fire the injectors. Mine did the same thing, but I replaced it and everything has been fine. I was going down the road and it flat out shut off in the middle of the highway. I had the clutch in trying to start it again, but it wouldnt so I called the local high preformance diesel shop 1 mile up the road. They brought out the part, put it in and it cranked right up.