The jig self aligns on the center fender support. Lightly clamp the jig to the frame. Use a 1/8" drill bit to create a pilot hole. Drill all the way through both sides of the frame. Next open the holes using a 5\16 bit. Ginz recommends a 23\64 bit but this jig aligns well enough to use a 5\16 which prevents excessive clearance and movement of the sissy bar when mounted.
The author marked this model as their own original creation.