Okay, I just ran across something interesting about the '37 bumpers. Drake sells one part number for both front and rear. Rock Valley shows two part numbers for passenger, one for truck. They use the same part number for the pass front, and both front and rear on pickup, then the different part number for the pass. rear. So, your original idea MAY still be right about different curvature. Still, they are flexible, so it may not make a difference.