I designed & built the rear bumper to bolt on using only the factory holes in the frame & the ones from the aftermarket receiver on the bottom of the frame rails. The front bumper uses only factory holes. The basic structure of this & my first front bumper is 3 pieces of hot-rolled C-channel.

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This bumper ended up weighing ~180# empty (when it was on the '83 frame).

See the NEXT few pics...