71 dart sway bar

73 and later had a sway bar routed through openings in the K frame. The earlier sway bar went around the front of the K. One Difference is the location of the end link tabs welded on the lower arms. Another difference is the earlier bars forward mounts were large, triangular, and hang a bit low. Curb bump stops would break the bolt ears off or worse. If you intend to keep the 71 K that doesn't have the openings I would suggest aftermarket sway bar(s). Hellwig, Addco, etc., wide range in price. Most of those have the end link tabs located on the lower shock attach bolt and smaller, more conventional type forward mounts.