First off did you start the pickup after you realized it had gas in the fuel tank? If not then the fix is typically pretty easy, we will drain and clean the tank, replace the fuel filters, refill it with diesel and it should be good to go. If you were unaware of the gas in the fuel tank and started it then we have a different route that we need to go down. The fuel tank needs to be dropped, cleaned and then refilled with diesel, the fuel filters will need to be replaced, then the fuel system bled to get the other fuel out of the system. At this point the fuel filters may need to be replaced again. At this point we will start testing each component for damage and then we will have a conversation about where to go depending on our findings. Worst case senario the engine will need to be replaced. Not the answer you wanted and it doesn't typically happen, but depending on the damage it could.
Give us a call and let us take care of you.