Some more information may help.
Truck? Grounding--pos or neg.?
This is strange, because the frame, cab body, doors, engine block, and everything else should be common to the ground. When you touch any part of the metal, you are the same potential as the truck ground and shouldn't be feeling anything!
Does this occur when you touch the door or some other metal part of the truck while sitting in the truck, standing on the running board or standing on the ground beside the truck?
Does it occur when you touch the door only, or if you touch some other metal part of the truck?
You said it occurs when you turn the ignition off and get out of the truck. What about it you shut the engine down, but leave the ignition on and get out or touch metal. Does it happen then?
Does your battery discharge at all?
One starting point would be to disconnect the positive (or "hot") battery cable. Make sure that eliminates the problem. Then with the battery cable once again disconnected, disconnect the wire to the ignition switch, but leave the primary cable connected to the starter switch (on a stomper starter) or to the solenoid (on a solenoid activated starter).
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