I am looking for 1/8" or 3/16" steel quarter panels for my 40. I have not been able to find steel only aluminum.  oes anyone know where I can get them?
I think you mean the rocker panels. No sweat with that
Go to your local welder and explain what you want. They will make you exactly what you need. Alternatively, you could go to lowes and spend about 30 bucks on some stout angle iron and bolt it to the rocker panel after you cut off the bottom.