Comparing the two boxes side by side, it's clear that the factory added clearance to the snout of the Fairlane box to allow it to clear the heavier framerail. We took our angle grinder and made a similar clearance on the snout of our Flaming River box. The bevel we added to our new box allowed the two front mounting holes to align perfectly, imparting the correct mounting angle to the new box. We then discovered that with the two front bolts installed, the rear mounting hole in the Fairlane framerail was in the wrong location to accommodate the Mustang box. Simply creating a new hole would allow us to complete the installation.