When I built my first set of stacks years ago, I made my own. Pretty simple little brackets really, if you have a welder and a torch. I took 1/4 plate cut two flat sections 2x5 inches (my cross pipe was 5 inch, the length of your pieces should be about the same as your cross pipe)these will be the part of the bracket that bolts to the bed floor. Cut two more pieces the same length and tall enough to go from your bed floor to about half way up your cross pipe, these will be the vertical part of the bracket from the bed floor to the cross pipe. Next take the vertical section and cut a half circle shape roughly the size of your cross pipe outside diameter on one end. Next weld the flat secton to the vertical section at a 90 deg angle (make an L), and weld the half circle cut onto the cross pipe. Drill the flat section and matching holes in the bed floor and bolt your stacks down. Take your time on the layout and welding to make sure everything is square and even to ensure your stacks are straight. I ran stacks on my truck for a little over a year with no problems, my buddy has had the same setup for 5 or 6 years with no problems. This is a very solid way to mount stacks, I could grab mine and shake the hell out of them, they didn't move a bit.
