On my 520 I am using some old metal shelving I got for free form work. Its aboot half a gauge thicker than the Datsun metal. I also used a little on my Volksrod Beetle. Turned out okay but I wish I had a brake for what I am doing to the truck. The bends are fine and will not be seen but mentally I know there not oem angles. If you want to check it out let me know. I have lots of the shelving and can get more if I need it.