67-71 Valiant rear bumpers are the same as 70-71 Duster/demon rear bumpers.
You still have to come up with a way to mount the earlier bracket, one of the mounting holes for the earlier bracket is right in the middle of the large “D” shaped hole where the shock mount brackets pass through the lower rear panel. There’s no frame tab on the end of the frame rail on the inside of th rails on the 74+ cars because the shock mount is there instead.
