If were to ever replace original or aftermarket drip rails, I would first install them with enough small self-tapping screws to form fit them to the cab.
I would then remove them and use 3M panel adhesive to affix them permanently to the cab, using all of those screws to clamp the drip rail in place. Once the adhesive has cured, I would remove the screws and fill the holes with more panel adhesive.
3M panel adhesive is a miracle in a tube and easy to sand butter smooth, those rails will never come off.
