The only pic I could find of mine, you need the newer GM style filler cover hinge that swings in so your marker light will be flush.
I tried to get a S-10 style door hinge to work so the hinge would flip the marker light up from the top
but it was a PITA
If ya go with a stock style tank you'll need to notch your bed support frame like this...
Its hard to see, but there it is