How to mount bumper over-ride 'nerf bars'

I bought a set of bumper overrides (bumperettes, nerf bars?) at a swap meet from a guy who had Cougar and Mustang parts. Decent, not show condition. They have mounting brackets on them, but I can’t figure out how they mount. Is there a source for images / diagrams of how these are supposed to mount? Perhaps they have Mustang brackets on them vs Cougar brackets. Thoughts?

Never mind. I looked at the ones in the online catalog, totally different brackets for them.