XP1K Mount Hardware

I am trying to install my intercom and car to car kit this weekend and I am having trouble with bracket hardware. First the opening for the intercom was not wide enough but with some manipulation and hand tongs I was able to rework the metal. Next I went to mount the intercom to the bracket and the hardware supplied does not allow you to do so. So I went up to Lowes thinking I could just get some M6 nuts and shorter screws and reverse hardware but the nuts are too thick and will not fit into the slot. What am I missing here. I am sure its something stupid. I did try calling rugged a little before 4PM but they were already closed. Thanks for any help in advanced I would like to try and get this project competed in the morning.