I have 2003 cc and I am putting on running boards. I am making a custom set of brackets, i want to use the nuts that are built into the rocker panels. Does anyone know what size bolts go into them?

I think they are 8mm.

You may want to consider using the body mount bolts instead. They will provide a much more solid mounting point...

Ox

Depending on where you are mounting the brackets Riv-Nuts might be another option.