One of the benefits of this rack is that when you don't need it, it stores nicely in the toolbox. Enjoy your new rack!
I recently purchased a short bed truck with a cross-bed toolbox and was faced with the dilemma of how to transport my bicycles. I thought about bolting fork mounts to the top of the toolbox but quickly dismissed the idea because it wouldn't work with the disc brakes on my mountain bike. Besides, I did not like the idea of drilling holes in the top of the toolbox. With my previous truck I had a piece of 2"x4" lumber with fork mounts bolted to it, that I set in the bed. I decided to try to figure out a way to attach the 2x4 to the top of the toolbox. The lid of the toolbox has a lip on the sides and back of the box and a continuous hinge across the front. The front of the bed of the truck has a lip between the bed and the cab. At first I thought of getting a longer 2x4 and using some J-bolts to attach it to the side lip of the toolbox. But then I remembered "The Donor".
The Donor was an inexpensive trunk mount bicycle rack that I had not used for years. It attached to the car with flat metal hooks attached to the bike rack with webbed strapping. I tried the hooks on the lip of the toolbox and found that they fit well. I disassembled the bike rack to remove the hooks and straps.