Re: ford ranger project start
That gap is so water can drain out of the bed. I have a Line-X and they left it open to allow the water to drain out. Mine's a 2004 no rust there. You could always shoot a coat of black rustoleum underneath the bed if you're worried about it rusting.
2004 XLT 4.0 4x4, 3" PA body lift, 32" BFG M/Ts, Dick Cepek DC-2 wheels, Euro tailights, self-painted headlight mod, NAV/DVD/XM/iPod stereo (Pioneer AVIC-D3), Line-X, Westin step bars, AVS bug shield and window vents