I have a 2018 Chevrolet Silverado double cab. I am trying to install running boards and the when I try put in the bolt under the truck, there is nothing to built into. The holes are there but nothing to bolt into

 

Welcome from Florida. Were there any bolts there that you removed? When I did my 2013, I had to remove the original bolts and replace them with longer ones to make it work. I am not familiar with the 2018, but it should be similar.

 

There was no bolts in there.