Need 1973 Duster Front Bumper Measurement

^^^This is incorrect information

73'- Early 74' will have the standard metal brackets
Late 74' to 76 will have shock bumper brackets

The late 74' to 76' have the outside mounting bolts spread out closer to the fenders than 73' to early 74' making them incompatible to swap

This has been confirmed on our Late build 74' Valiant and through comparing it against my 73' Duster bumper.
This is also evident by the fact that our early build 74 Swinger has the standard style mounting brackets
Yes, I agree about the LATE 74 being the same as 75/6, but the vast majority of 74's have the earlier design.
Either way, the OP asked about dimensions, and they are the same for all 73-76 cars.