SB, that’s right; I used threaded couplers that are an inch long I believe, and welded them to the inside of the tank. The threaded rods go in the couplers, leaving room for the mounting screws outside, top and bottom. When the threaded rods are set to the exact height I tack them in place. Remember to clean the inside as you go so your tank sealer; Por 15 or whatever brand you use, bonds well.