I had some large angle brackets hanging around so I drilled holes to match the two bolt hole on each side of the sissy bar. Then I used pipe spacers and bolts to attach them to support the base of the top case. But since the angle brackets were only about 3 inches long I cut a support board out of a thick plastic cutting board ( I love that material for projects ) Then mounted the top case base to that but had to support it further with two bars from the bottom bolt on the angle bracket to the further bolt on the top case base. It was rather complex as you can tell but I was determined to get a top case on there. I can take some pictures if you need them.