My k is from a 72 duster so yes the bar design is different but the ends if I remember correctly are the same stock design. The aftermarkets do definitely have differences.
The change was at ‘73. The ‘72 bar would have used the 67-72 style tabs, which are all the way out at the end of the LCA. The ‘73+ sway bars put the tab further in. Basically the 67-72 bars put that tab outside the strut rod, the ‘73+ bars put it inside of the strut rod.
The 67-72 bars work better with the shock bolt mount.
As for the aftermarket bars, they actually all pretty much use either the 67-72 or the 73+ tab location. Where things get interesting is bars like the Hotchkiss or Hellwig’s “pro touring” bar for the 67-72 cars. Those bars mount like the 67-72 so they can be used on those K frames, but the tabs are basically located at the 73+ position (for tire clearance).
