Frame differences in 67-72?

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I have what I am told, is a 69 short bed truck. The cab is obviously been removed and put back on so now I'm not sure if the fram I have is actually a 69 or not. I am putting on a 67 cab and front clip. My question is, is there any difference in the frames? I want to convert to disk up front and want to make sure I get the right parts. The "69" frame has 6 lug drums all the way around so that narrows it down to older then I think 71. It has a factory sway bar as well. Are the ball joints different? Would I be better off by putting the 67 suspension parts on the short frame so that I would know exactly what I had? A lot of questions I know.
Thanks for the info...