thebigredrocker
SILVER Star
If you don't want to repair the rotted channel or buy new running boards. Cut a rectanguler chunk of steel that will fit in the channel. Make it long enough to span the blown out channel and rest on what's left of the channel. Drill a hole for your M10 bolt and tack weld the bolt to the rectanguler "washer". You can tighten nut from under support bracket and bolt won't spin
I used some scrap rubber horse trailer mat to sandwich between the support bracket and running board channel. Thrift stores often have old heavy duty neoprene wetsuits cheap. You could cut and stack layers of neoprene to reach correct thickness.
Love Bug+Bug's Dad searching for Neoprene scraps=more memories