I'm aware of the differences. I have an '83 Bronco with this bumper as well. I am adding a contour bumper to my '96 now :) I do have an older set of contour brackets and I have started modifying them. The bumper shape never changed, so it's just about mounting them to the frame rail. But I haven't finished, so I'm still open at this point. You tell me what you want , . otherwise I'll just finish what I'm doing :)
Pete's Ponies
Mustang RUSToration & Performance
1982 F100 Flareside
1983 Bronco