Here’s a FabBoss trimmed and angled to fit along the rear firewall of our Project Unfair. I cut it and used a belt sander to give it the proper angle. The idea is to bolt the FabBosses to the part being installed, position it in place, and then weld it. You end up with perfect alignment, without having to drill precisely measured holes, and without a bolt protruding into the space behind. Having the tray raised off the body’s floor by FabBosses gives us room to route harnesses underneath and bring them up through holes to the device.