Looking for bolts & nuts for running boards

I bought a 2001 Jeep Wrangler Sahara edition and it came with the running boards, but not mounted. Went to the local jeep dealert and ordered the nuts and 'rivnuts' to install. When they arrived. They Were Too small for the pre-drilled holes. Anyone know where I can find the right ones? I went to fastenal and they only had the same size as the dealer sold me.
Thanks
Charlie

Looking for bolts & nuts for running boards