The one on my car (above) has the bumper jack holes towards the outside of the bumper. I believe it to be 74 and up. The ones with this posting is a 73 (I think). The bumper jack hole is a little closed to the center of the car. Also a 73 does not have as many holes. No lower holes on the out side edge.
No way of knowing if it is original to the car or not, but this is the bumper that was on the 73 Sport my son dragged home. It has the extra holes that you do NOT want. Maybe another early vs. late application??
Ah, good, so you do understand that you just can't bolt the '73 bumper up to the '74 shock mounts. Using the '73 bumper either requires making a set of intermediate brackets to go between the shock mounting location and the regular '73 brackets to use the '73 bumper, or welding up and reinforcing the tail panel to match the earlier cars and using the '73 brackets. Getting the '73 bumper on is relatively easy, making it look factory requires a decent amount more work.