As far as where to weld the tank braces on: measure the distance between the grooves on the tank where the straps go from center to center (of the grooves). The brackets are going to be welded on the floor with the same center-to-center spacing. If you're using the two piece floor, put them together upside down on the floor, mark the center, and then measure to each side half of the distance you measured between the tank groove centers. I think the grooves are 10" apart on center, so the braces are welded on 5" from the floor centerline to center of the brace on each side. Obviously the front of the brace wraps around the bend in the floor (the curve didn't quite fit on the two we did). Good luck.