It pretty much determines the layout of your conversion, for instance, I used a 4x4x.25 tube and then sandwiched a piece of rubber between the tube and the frame of the truck and then u-bolted it down. On top of the 4'' tube I ran 2x3x.188 rectangular tube 16''o.c. Maybe a little heavy but I don't want the rattle and all the twisting associated with cheaper built units. I also have 3 large slide outs which decreases my wall strength, so by adding strengh to the floor and the roof, I can justify these slides. Also the more weight you put on these trucks the better your braking and ride will be, try bob tailing one and then driving a loaded one, see which one handles better. Take a look at my gallery and see if it helps
__________________
|