Can you try aligned the bracket to the bumper and drill new mounting holes on the bumper or brackets? You might want to order a universal mounting bracket from Westin to make it work. I have done this to the rear bumper on my 1984 Chevy Stepside and it turned out terrific. I actually installed a after-market bumper designed for Chevy Luv Truck with universal brackets onto my Chevy shortbed by measuring and refitting over and over again to get the perfect leveled fit I wanted and at the end of the day, they mated perfectly.