I bolted the supports to the body using the bottom holes. For the top I just used top holes of the supports as my guide drilled through the body and bolted it to the supports with the hex bolts. Where do the u-bolts come in? Well I found with the added rigidity of my new dinosaur the swing itself started to bind up when in motion. My solution was to add an additional point of articulation to the tops of the front two supports. I used the u-bolt to mark my holes, drilled them out, installed the u-bold and loosely put the two nuts on. Then cut out about a 1/4" section in between the bolt with a hacksaw. Took them out, put a plate on the back, reinstalled the bolts, put a plate on the front and bolted them down.