Hi Harold:
I used carriage bolts for the running boards to frame/running board supports.(They are captured in the running board. I used 1/4 20 for the running board to fender. I recall you have to put the nut on the fender side because at least one of the bolts is so tight against the running board there is no room to put a nut on the running board side. I also used fender washers. The splash guards from the bed to the running board I also recall using carriage bolts. I get to move back to WA later this summer so I can take pictures if you need them. You will probably be done by then!