I saw caribou cases and I thought instead of buying a 350$ top case for my motorcycle, I went to bandh.com and grabbed a hprc case for 80 bucks. I then went to ace hardware and spent about 15 bucks on screws and washers.
Step 1: Pull Off Rack From Bike
Lay your rack on top and measure to the center of the case. so you know where to drill the holes.
Put bolts through. My rack had spots for the bolts to lock into place. I put nuts there to raise the case since it is not flat on the bottom.
Step 2: Nylon Washers
Your case sits on these
Step 3: Mount Case
Mount the case and add your washers.
Step 4: Bolt It Down
I used lock nuts.