I have built 2 sets out of 4x4x1/4 tube with 1/4" square plates on top. I was able to cut a 30 degree angle on the bottom so they do not hang below the frame. They are a little over kill and heavy but look cool. Drilled 1/2 holes in square plate to hold universal urethane mounts. Set your cab on blocks where you like it and weld them on and remove the blocks. Level and locate twice, weld once. Good luck!
