Pretty sure the ‘74 bumper with the 5 mph shocks is the same as the ‘75-76 bumper. Not sure but I would bet the ‘73 and ‘74 bumper are the same if the ‘74 didn’t have the shocks. I know the bolt holes are in different places between the non-shock and shock bumpers.
Either way, the shape is pretty much the same from ‘73-76. The brackets would be different though, depending on the bumper mounts. Not sure if the tab you are using on the bumper exists on the shock mounted bumper though, will look at mine later this morning.