Park the truck on a incline so the fuel will run out of the valley. Brake clean the crap out of the valley and dry it with compressed air. Start the truck use a good flashlight get a automotive inspection mirror and start hunting.
I'm with everyone else don't tear into this thing until you have a real good idea where this leak is coming from. You can easily spend a ton money & not fix the leak.
my guess is the cup plug on the bottom of the pump will be blown out