I believe b-bodies certainly had them by 74. I've never seen a true 74 b-body door without them. Having said that, I know that one should never say never! I do have a 73 door for my 74 Road Runner and it does not have the bar. By the way there is a noticeable difference in weight between the two. My 74 Road Runner was built in early Dec of 73. I do not know the date for the 73 door that I have (the one without the bar) so perhaps spank04 is right with mid 73???