Pretty much. 1974 had an extra hole on the end with a bumper bolt. At some time...that outside hole was not made in the bumpers. I don't know if 1975 is the cut off year or not.
unless you have "the eye" for it like craig, the average person cant tell the diffrence between '74-77 bumpers lol. untill i read that i didnt know, im going to look tomorrow for that bolt