My '76 had the shifter cutout location, and boot screw locations, marked with dimples on the side of the hump. Other than that, the only difference was mounting brackets welded to the floor near the front and rear of the console. I removed the console and brackets from the donor car, so was able to get the dimensions for the bracket locations. I just used large sheet metal screws to fasten them to the floor.
The hump shape between the '70 Duster donor car and the '76 Dart SE was identical.