Installed 1970 duster front bumper 0n my 1975 duster

Nice work!

Did you drill all the way through the frame rails, or add a captured nut for the bumper bolt you have since your '75 probably wouldn't have had the mounts for the non-shock brackets?

It looks like you could just put a small notch in the bumper to keep it from hitting the lower fill panel. Or maybe even a larger angled section that tapers in to mask the angle between the bumper and the filler?