I installed the B&W myself. In my case I had to cut approx 1" pyramid shape cut in the bottom side of a bed lip. This was access to slide in one of the cross members. Had to cut out a section of heat shield on my model, tuff but doable with tin snips. The big hole I used a cheap hole saw with a oiled sponge fitted inside. I only installed one of the safety chain hooks due to accessibility with drill and not planning on using a gooseneck. You don't need chains on a 5er hitch. As stated used holes in the frame. Bolts had handles attached that you feed through one hole to reach inside the frame and feed the bolt through another hole to attach brackets.